Mairsil does not have summoning sickness.

Activate Mairsil using Gilded Lotus' ability by tapping it, adding .
Activate Mairsil using Morphling's first ability by paying , untapping Mairsil.
Activate Mairsil using Quicksilver Elemental's ability by paying , causing Mairsil to gain all activated abilities of itself until end of turn.
Repeat.

Experiment Kraj does not have summoning sickness.

Activate Experiment Kraj by tapping it, putting a +1/+1 counter on Morphling.
Activate Experiment Kraj using Morphling's ability by paying , untapping it.
Activate Experiment Kraj by tapping it, putting a +1/+1 counter on Incubation Druid.
Activate Experiment Kraj using Morphling's ability by paying , untapping it.
Activate Experiment Kraj using Incubation Druid's ability by tapping it, adding at least .
Repeat from step 4.

Experiment Kraj does not have summoning sickness.
You control up to two lands that can produce a total of at least .

Activate up to two lands you control by tapping them, adding at least .
Activate Experiment Kraj by tapping it, putting a +1/+1 counter on Morphling.
Activate Experiment Kraj using Morphling's ability by paying , untapping it.
Activate Experiment Kraj by tapping it, putting a +1/+1 counter on Argothian Elder.
Activate Experiment Kraj using Morphling's ability by paying , untapping it.
Activate Experiment Kraj using Argothian Elder's ability by tapping it, untapping up to two lands.
Activate up to two lands you control by tapping them, adding at least .
Repeat from step 5.

Mimeoplasm does not have summoning sickness and has power 6 or greater.
Morphling and Kami of Whispered Hopes are exiled by Mimeoplasm.

Activate Mimeoplasm by paying , causing it to become a copy of Kami of Whispered Hopes.
Activate Mimeoplasm by tapping it, adding at least six .
Activate Mimeoplasm by paying , causing it to become a copy of Morphling.
Activate Mimeoplasm by paying , untapping it.
Repeat.

Experiment Kraj does not have summoning sickness.
You control up to two lands that can produce a total of at least .
You have at least seven cards in your graveyard.

Activate up to two lands you control by tapping them, adding at least .
Activate Experiment Kraj by tapping it, putting a +1/+1 counter on Morphling.
Activate Experiment Kraj using Morphling's ability by paying , untapping it.
Activate Experiment Kraj by tapping it, putting a +1/+1 counter on Krosan Restorer.
Activate Experiment Kraj using Morphling's ability by paying , untapping it.
Activate Experiment Kraj using Krosan Restorer's ability by tapping it, untapping up to two lands.
Activate up to two lands you control by tapping them, adding at least .
Repeat from step 5.

You control a land that can tap to produce .
Marvin does not have summoning sickness and has at least one +1/+1 counter on it.

Activate Marvin using Incubation Druid's ability by tapping it, adding .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

Marvin does not have summoning sickness.

Activate Marvin using Kami of Whispered Hopes's ability by tapping it, adding at least .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

You control a creature with power 7 or greater.
Mimeoplasm does not have summoning sickness.
Morphling and Selvala are exiled by Mimeoplasm.

Activate Mimeoplasm by paying , causing it to become a copy of Selvala.
Activate Mimeoplasm by paying and tapping it, adding at least .
Activate Mimeoplasm by paying , causing it to become a copy of Morphling.
Activate Mimeoplasm by paying , untapping it.
Repeat.

Quicksilver Elemental has at least one +1/+1 counter on it.
Quicksilver Elemental does not have summoning sickness.

Activate Quicksilver Elemental twice by paying , causing it to gain all activated abilities of Incubation Druid and Morphling until end of turn.
Activate Quicksilver Elemental using Incubation Druid's first ability by tapping it, adding .
Activate Quicksilver Elemental using Morphling's first ability by paying , untapping it.
Repeat from step 2.

Marvin does not have summoning sickness.

Activate Marvin using Gyre Engineer's ability by tapping it, adding .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

Experiment Kraj does not have summoning sickness.
Morphling and Ley Weaver each have at least one +1/+1 counter on it.
You control up to two lands that can tap to produce at least .

Activate Experiment Kraj using Ley Weaver's ability by tapping it, untapping two lands you control.
Activate a land by tapping it, adding at least .
Activate Experiment Kraj using Morphling's first ability by paying , untapping Experiment Kraj.
Repeat.
You may tap an additional land each cycle to get infinite mana, and you may then use Experiment Kraj's ability to put infinite +1/+1 counters on creatures you control.

Two lands that tap for blue.

Pay using Quicksilver Elemental to target Morphling.
Pay using Quicksilver Elemental to target Argothian Elder.
Tap Quicksilver Elemental for at least .
Pay to untap Quicksilver Elemental.
Repeat.

Activate Marvin using Argothian Elder's ability by tapping it, untapping two lands you control.
Activate the two lands by tapping them, adding at least .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

Mimeoplasm does not have summoning sickness and has power 6 or greater.
Morphling and Heronblade Elite are exiled by Mimeoplasm.

Activate Mimeoplasm by paying , causing it to become a copy of Heronblade Elite.
Activate Mimeoplasm by tapping it, adding at least six .
Activate Mimeoplasm by paying , causing it to become a copy of Morphling.
Activate Mimeoplasm by paying , untapping it.
Repeat.

Activate Morphling by tapping it, adding .
Kinnan triggers, adding .
Activate Morphling by paying , untapping it.
Repeat.

Once you have infinite , you can instead tap for other colors of mana. Notably, you can tap for to use Kinnan's ability.

You control a creature with power 4 or greater.
Marvin does not have summoning sickness.

Activate Marvin using Ilysian Caryatid's ability by tapping it, adding .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

You control a creature with power 9 or greater.

Activate Likeness Looter by paying , causing it to become a copy of Selvala.
Activate Likeness Looter using Selvala's ability by paying and tapping it, adding at least .
Activate Likeness Looter by paying , causing it to become a copy of Morphling.
Activate Likeness Looter using Morphling's first ability by paying , untapping it.
Repeat.

Activate Morphling by tapping it, adding .
Kinnan triggers, adding .
Activate Morphling by paying , untapping it.
Repeat.

Once you have infinite , you can instead tap for other colors of mana. Notably, you can tap for to use Kinnan's ability.

Activate Morphling by tapping it, adding .
Kinnan triggers, adding .
Activate Morphling by paying , untapping it.
Repeat.

Once you have infinite , you can instead tap for other colors of mana. Notably, you can tap for to use Kinnan's ability.

Activate Marvin using Ley Weaver's ability by tapping it, untapping two lands you control.
Activate the two lands by tapping them, adding at least .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

Marvin does not have summoning sickness.

Activate Marvin using Selvala's ability by paying and tapping it, adding at least .
Activate Marvin using Soliton's ability by paying , untapping it.
Repeat.

Activate Morphling by tapping it, adding .
Kinnan triggers, adding .
Activate Morphling by paying , untapping it.
Repeat.

Once you have infinite , you can instead tap for other colors of mana. Notably, you can tap for to use Kinnan's ability.

Activate Marvin using Bloom Tender's ability by tapping it, adding at least .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

Activate Machine God's Effigy by tapping it, adding .
Kinnan triggers, adding .
Activate Machine God's Effigy by paying , untapping it.
Repeat.

Morphling can be in any zone so long as Machine God's Effigy is on the battlefield as a copy of it.

You have at least six creature cards in your graveyard.
Mimeoplasm does not have summoning sickness.
Morphling and Deathbloom Ritualist are exiled by Mimeoplasm.

Activate Mimeoplasm by paying , causing it to become a copy of Deathbloom Ritualist.
Activate Mimeoplasm by tapping it, adding at least six .
Activate Mimeoplasm by paying , causing it to become a copy of Morphling.
Activate Mimeoplasm by paying , untapping it.
Repeat.

Marvin does not have summoning sickness.

Activate Marvin using Heronblade Elite's ability by tapping it, adding at least .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

Song of Freyalise's first or second chapter ability has triggered this turn.

Activate Morphling by tapping it, adding .
Kinnan triggers, adding .
Activate Morphling by paying , untapping it.
Repeat.

Once you have infinite , you can instead tap for other colors of mana. Notably, you can tap for to use Kinnan's ability.

Morphling does not have summoning sickness.

Activate Morphling by tapping it, adding .
Activate Morphling's first ability by paying , untapping it.
Repeat.

Paradise Mantle attached to Morphling.
Morphling does not have summoning sickness.

Activate Morphling by tapping it, adding .
Morphling triggers, causing you to loot.
Activate Morphling's first ability by paying , untapping it.
Repeat.

Illusionist's Bracers and Paradise Mantle attached to Morphling.
Morphling does not have summoning sickness.

Activate Morphling by tapping it, adding .
Activate Morphling's first ability by paying .
Illusionist's Bracers triggers, copying Morphling's ability.
Resolve the copy of Morphling's ability, untapping it.
Activate Morphling by tapping it, adding one mana of any color.
Resolve Morphling's ability from step 2, untapping it.
Repeat.

Morphling does not have summoning sickness.

Activate Morphling by tapping it, adding .
Activate Morphling's first ability by paying , untapping it.
Repeat.

Activate Morphling by tapping it, adding .
Kinnan triggers, adding .
Activate Morphling by paying , untapping it.
Repeat.

Once you have infinite , you can instead tap for other colors of mana. Notably, you can tap for to use Kinnan's ability.

Activate Marvin using Arbor Adherent's ability by tapping it, adding at least .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

Marvin does not have summoning sickness.

Activate Marvin using Sage of the Maze's ability by tapping it, adding .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

Activate Machine God's Effigy by tapping it, adding .
Activate Machine God's Effigy by paying , untapping it.
Repeat.

Cast Machine God's Effigy by paying , choosing to have it enter the battlefield as a copy of Morphling that is an artifact.
Activate Machine God's Effigy by tapping it, adding .
Activate Machine God's Effigy by paying , untapping it.
Mesemeric Orb triggers, causing you to mill a card.
Repeat from step 2.

Necrotic Ooze does not have summoning sickness.

Activate Necrotic Ooze using Zaxara's ability by tapping it, adding .
Activate Necrotic Ooze using Morphling's first ability by paying , untapping Necrotic Ooze.
Repeat.

Activate Machine God's Effigy by tapping it, adding .
Activate Machine God's Effigy by paying , untapping it.
Repeat.

Illusionist's Bracers attached to Morphling.
Morphling does not have summoning sickness.

Activate Morphling by tapping it, adding .
Activate Morphling's first ability by paying .
Illusionist's Bracers triggers, copying Morphling's ability.
Resolve the copy of Morphling's ability, untapping it.
Activate Morphling by tapping it, adding one mana of any color.
Resolve Morphling's ability from step 2, untapping it.
Repeat.

Mairsil does not have summoning sickness.
Your devotion to blue is at least three.

Activate Mairsil using Nyx Lotus' ability by tapping it, adding at least .
Activate Mairsil using Morphling's first ability by paying , untapping it.
Activate Mairsil using Quicksilver Elemental's ability by paying , causing it to gain all activated abilities of itself until end of turn.
Repeat.

Cast Machine God's Effigy by paying , choosing to have it enter the battlefield as a copy of Morphling that is an artifact.
Activate Machine God's Effigy by tapping it, adding .
Activate Machine God's Effigy by paying , untapping it.
Wake Thrasher triggers, giving itself +1/+1 until end of turn.
Repeat from step 2.

Activate Morphling by tapping it, adding .
Kinnan triggers, adding .
Activate Morphling by paying , untapping it.
Repeat.

Once you have infinite , you can instead tap for other colors of mana. Notably, you can tap for to use Kinnan's ability.

You control at least two enchantments.
Marvin does not have summoning sickness.

Activate Marvin using Sanctum Weaver's ability by tapping it, adding at least .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

Activate the basic land with Fertile Ground attached by tapping it, adding at least .
Fertile Ground triggers, adding .
Activate Earthcraft by tapping Morphling, untapping the basic land.
Activate Morphling's first ability by paying , untapping it.
Repeat.
If the basic land is an Island, you may add mana of any color using Fertile Ground's trigger, and you may infinitely repeat steps 3-4 with any other basic land you control.

Activate Marvin using Faeburrow Elder's ability by tapping it, adding at least .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

Patchwork Crawler does not have summoning sickness.

Activate Patchwork Crawler using Zaxara's ability by tapping it, adding .
Activate Patchwork Crawler using Morphling's first ability by paying , untapping Patchwork Crawler.
Repeat.

Activate Steelswarm Operator's second ability by tapping it, adding that can only be spent to activate abilities of artifacts.
Activate Steelswarm Operator using Morphling's ability by paying , untapping it.
Repeat.

Once you have infinite mana, you can use Steelswarm Operator's first ability instead.

Morphling does not have summoning sickness.
Morphling has at least one +1/+1 counter on it.

Activate Morphling by tapping it, adding .
Activate Morphling's first ability by paying , untapping it.
Repeat.

Morphling does not have summoning sickness.

Activate Morphling by tapping it, adding .
Activate Morphling's first ability by paying .
Crackdown Construct triggers, giving itself +1/+1 until end of turn.
Resolve the Morphling ability, untapping it.
Repeat.

You control another creature with toughness 6 or greater.

Activate Mimeoplasm by paying , causing it to become a copy of Arbor Adherent.
Activate Mimeoplasm by tapping it, adding at least six .
Activate Mimeoplasm by paying , causing it to become a copy of Morphling.
Activate Mimeoplasm by paying , untapping it.
Repeat.

You control at least two Allies.
Marvin does not have summoning sickness.

Activate Marvin using Harabaz Druid's ability by tapping it, adding at least .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

Illusionist's Bracers and Karametra's Favor attached to Morphling.
Morphling does not have summoning sickness.

Activate Morphling by tapping it, adding .
Activate Morphling's first ability by paying .
Illusionist's Bracers triggers, copying Morphling's ability.
Resolve the copy of Morphling's ability, untapping it.
Activate Morphling by tapping it, adding one mana of any color.
Resolve Morphling's ability from step 2, untapping it.
Repeat.

Morphling does not have summoning sickness.
Morphling has at least one +1/+1 counter on it.

Activate Morphling by tapping it, adding .
Activate Morphling's first ability by paying , untapping it.
Repeat.

Market Festival attached to Morphling.
Morphling does not have summoning sickness.

Activate Morphling by tapping it, adding .
Market Festival triggers, adding and one mana of any color.
Activate Morphling's first ability by paying , untapping it.
Repeat

Morphling does not have summoning sickness.
Song of Freyalise has one or two lore counters on it.

Activate Morphling by tapping it, adding .
Activate Morphling's first ability by paying .
Crackdown Construct triggers, giving itself +1/+1 until end of turn.
Resolve the Morphling ability, untapping it.
Repeat.

Marvin does not have summoning sickness.

Activate Marvin using Selvala's ability by tapping it, adding at least .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

You have at least two creature cards in your graveyard.
Marvin does not have summoning sickness.

Activate Marvin using Deathbloom Ritualist's ability by tapping it, adding at least .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

Necrotic Ooze does not have summoning sickness.
You have at least one nonland card in hand.

Activate Necrotic Ooze using Codie's ability by paying and tapping it, adding .
Activate Necrotic Ooze using Morphling's first ability by paying , untapping Necrotic Ooze.
Repeat as desired, skipping step 2 on the final iteration.
Cast any spell by paying its mana cost, reduced by the added in step 1.
Necrotic Ooze triggers for each time you activated Codie's ability.
Resolve the first trigger, causing you to exile cards from the top of your library until you exile an instant or sorcery spell with lesser mana value, and allowing you to cast that spell without paying its mana cost.
Repeat step 6 for each remaining trigger.
You may also repeat this combo for each nonland card in your hand as mana permits, and on subsequent turns.

Marvin does not have summoning sickness.

Activate Marvin using Blossom-Clad Werewolf's ability by tapping it, adding .
Activate Marvin using Soliton's ability by paying , untapping it.
Repeat.

There are at least two Elves on the battlefield.
Marvin does not have summoning sickness.

Activate Marvin using Wirewood Channeler's ability by tapping it, adding at least .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

You control at least two creatures with defender.
Marvin does not have summoning sickness.

Activate Marvin using Axebane Guardian's ability by tapping it, adding at least .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

You have gained at least 2 life this turn.
Marvin does not have summoning sickness.

Activate Marvin using Accomplished Alchemist's ability by tapping it, adding at least .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.

Your commander on the battlefield as a creature and does not have summoning sickness.
Your commander has a power of eight or greater.

Activate your commander by paying , causing it to become a copy of Heronblade Elite until end of turn.
Activate your commander by tapping it, adding at least eight .
Activate your commander by paying , causing it to become a copy of Morphling until end of turn.
Activate your commander's first ability by paying , untapping it.
Repeat.

Your commander on the battlefield as a creature and does not have summoning sickness.
You have gained at least eight life this turn.

Activate your commander by paying , causing it to become a copy of Accomplished Alchemist until end of turn.
Activate your commander's second ability by tapping it, adding at least eight .
Activate your commander by paying , causing it to become a copy of Morphling until end of turn.
Activate your commander's first ability by paying , untapping it.
Repeat.

There are at least six Elves on the battlefield.
Mimeoplasm does not have summoning sickness.
Morphling and Wirewood Channeler are exiled by Mimeoplasm.

Activate Mimeoplasm by paying , causing it to become a copy of Wirewood Channeler.
Activate Mimeoplasm by tapping it, adding at least six .
Activate Mimeoplasm by paying , causing it to become a copy of Morphling.
Activate Mimeoplasm by paying , untapping it.
Repeat.

You have gained at least 6 life this turn.
Mimeoplasm does not have summoning sickness.
Morphling and Accomplished Alchemist are exiled by Mimeoplasm.

Activate Mimeoplasm by paying , causing it to become a copy of Accomplished Alchemist.
Activate Mimeoplasm by tapping it, adding at least six .
Activate Mimeoplasm by paying , causing it to become a copy of Morphling.
Activate Mimeoplasm by paying , untapping it.
Repeat.

Elemental Mastery attached to Morphling.
Morphling does not have summoning sickness.

Activate Morphling by tapping it, creating three 1/1 Elemental creature tokens with haste.
Activate an Elemental token by tapping it, adding .
Activate Morphling's first ability by paying , untapping it.
Repeat.

Necrotic Ooze does not have summoning sickness.

Activate Necrotic Ooze using Jegantha's ability by tapping it, adding that cannot be spent to pay generic mana costs.
Activate Necrotic Ooze using Morphling's first ability by paying , untapping Necrotic Ooze.
Repeat.

Activate Marvin using Avatar Kyoshi's ability by tapping it, adding at least .
Activate Marvin using Morphling's ability by paying , untapping it.
Repeat.