There are many alternative card choices for this deck. It is quite possible to drop the handful of black cards and use Ink-Treader Nephilim as commander, if legality is not a concern. This also allows you to switch to a 4-color mana base instead.
Chaos Warp can also act like Polymorph with help from Ink-Treader Nephilim, Zada, Hedron Grinder, Mirrorwing Dragon, or Radiate, but also finds non-creature permanents like a Primal Surge. This should replenish your mana by putting into play lands, mana rocks, and possibly mana creatures with Chasm Guide for haste, and Sea Gate Loremaster for card draw. It does require a very large number of targets to get good value out of it, because although it starts out with about 70% chance of putting a permanent into play, the probability gets lower as more permanents are taken out of the library and put into play.
Brudiclad, Telchor Engineer can turn all your tokens into another creature if you have Heat Shimmered that creature. Divine Visitation turns all your tokens into Serra Angels.
Twinflame and Cackling Counterpart can become Clone Legion when targeting Zada, Hedron Grinder or Mirrorwing Dragon, but can't copy opponents' creatures when targeting Ink-Treader Nephilim unlike Heat Shimmer. Fated Infatuation is harder to cast but will also scry very deep into your deck. Spitting Image costs a lot of mana but gets exponential if retraced, especially with token-doubling enchantments. Rite of Replication permanently copies creatures, and if kicked targeting Ink-Treader Nephilim is like casting Clone Legion 5 times for each player. Supplant Form targeting Ink-Treader Nephilim essentially gives you control of everyone's creatures, and flickers our Allies for their triggered abilities while bouncing the originals so you can cast them to trigger even more. Quasiduplicate is a reusable copy effect. Mark of Mutiny and Besmirch also steal opponents' creatures and give all creatures haste.
Crafty Cutpurse can turn all tokens created into your tokens, by flashing it in or by killing the Cutpurse and reanimating it with Cauldron of Souls or Thrilling Encore.
Conqueror's Pledge, Increasing Devotion, Nomads' Assembly, and Deploy to the Front can make an army of tokens quickly. Chasm Skulker and The Locust God create lots of Insects and Squids thanks to your cantrips. Spawning Breath is also a good followup to Mercy Killing on Ink-Treader Nephilim, turning everyone's Elves into our Eldrazi Spawn for further transformation or mana. Launch the Fleet can multiply your army when you attack. Empty the Warrens potentially makes a lot of Goblins during the turn you go off. Mitotic Slime splits into more and more tokens when you transform it. Gutter Grime can generate very big Ooze tokens especially with Doubling Season to double the slime counters. Sek'Kuar, Deathkeeper and Ogre Slumlord also generate lots of tokens from nontoken creatures dying. Requiem Angel generates lots of tokens from both token and nontoken creatures dying. Tooth and Claw gives infinite ETB triggers with one token-doubling enchantment in play, and makes infinite tokens with two token-doubling enchantments.
Primal Vigor appears to be a double-edged sword compared to Doubling Season since it gives opponents double the tokens as well, but it is superior if you can steal all those tokens afterwards. Gather Specimens steals all opponents' tokens when you cast Descent of the Dragons or target Ink-Treader Nephilim with removal.
Hellion Eruption also works like Emrakul's Evangel.
Contract Killing can transform all creatures into your Treasure, which is good for comboing off if you can recur or summon creatures and generate tokens after that. Battle Hymn gives you mana for each of your creatures without killing them. Jeskai Ascendancy untaps mana creatures so you can keep casting spells, while pumping your creatures and looting for cards. Sylvan Awakening also animates your lands so they can be untapped by Jeskai Ascendancy. Paradox Engine untaps your creatures and mana rocks. Twitch can also untap lands and artifacts and draw cards for each of those, making it amazing with Radiate (although untapping opponents' permanents can be risky).
Alternative ramp cards to consider are Gemhide Sliver, Manaweft Sliver, Sylvan Caryatid, Fellwar Stone, Cryptolith Rite, Knotvine Mystic, Xenagos, the Reveler, Pir's Whim, Tempt with Discovery, Coalition Relic, Utopia Sprawl, Wild Growth, Mirari's Wake, and Seedguide Ash.
Graceful Reprieve and Reincarnation become mass recursion when targeting Zada, Hedron Grinder or Mirrorwing Dragon, with Reincarnation having the advantage of reanimating any creature in your graveyard even when a token dies. Cauldron Haze targeting Zada, Hedron Grinder or Mirrorwing Dragon can give your creatures persist. Mikaeus, the Unhallowed recurs all your non-Humans. Rally the Ancestors easily reanimates all your creatures since their mana costs are low. Patriarch's Bidding choosing Ally also works if you don't expect opponents to have tribal decks, or aren't worried about them. Second Sunrise also helps opponents bring back their permanents, which can be exploited if you have Tuktuk Scrapper to burn them.
Elesh Norn, Grand Cenobite makes opponents' tokens much smaller and yours much bigger. Opponents' Elves all die after Mercy Killing, and they will have no lands after Natural Affinity.
Vela the Night-Clad acts as a counterpart to Purphoros, God of the Forge, while also making your Eldrazi Horrors unblockable.
Legion Loyalist is an interesting source of evasion if you can transform all opponents' creatures into tokens. Champion of Lambholt is also great. Stun is a cantrip that makes your creatures unblockable if it targets Ink-Treader Nephilim.
Accelerate gives your creatures haste while drawing cards.
Might of the Masses and Sigil Blessing pump your creatures by a lot. Rally the Righteous pumps them a lot and untaps them. Blossoming Defense and Vines of Vastwood pumps them while granting hexproof. Confront the Unknown also pumps them while generating Clue tokens. Wild Defiance turns other targeted spells into Giant Growths. Cathars' Crusade is an easy way to grow your creatures when lots of them enter play.
Tuktuk Scrapper deals more damage to opponents while destroying problematic artifacts. Ondu Cleric gives massive amounts of life. Halimar Excavator mills out opponents instead of burning. Bala Ged Thief discards opponents' hands. Agadeem Occultist brings back opponents' creatures under your control. Kor Entanglers taps opponents' creatures so you can attack without getting blocked. Hero of Goma Fada makes your creatures indestructible so your spells create tokens without destroying the original creatures, but this also means they don't go to the graveyard so you can't reanimate them to trigger their abilities again. Jwari Shapeshifter can copy any Ally creature you have.
Ember-Fist Zubera can deal a lot of damage if copied with Polymorphous Rush before sacrificing all of them to Emrakul's Evangel or Descent of the Dragons.
Dovescape prevents players from casting noncreature spells and generates lots of Birds, but the copies from spells targeting Zada, Hedron Grinder, Mirrorwing Dragon, or Ink-Treader Nephilim don't get countered, which you can use to your advantage.
Kira, Great Glass-Spinner prevents your creatures from dying to the first targeted spell, so you can target Ink-Treader Nephilim for a one-sided boardwipe. Nivmagus Elemental is even better as it allows you to choose which spells resolve and which don't by exiling any of the copied spells, so every spell you cast is to your advantage, with no collateral damage to the creatures you want to keep.
