When Day of the Dragons enters the battlefield, exile all creatures you control. Then create that many 5/5 red Dragon creature tokens with flying. When Day of the Dragons leaves the battlefield, sacrifice all Dragons you control. Then return the exiled cards to the battlefield under your control.

Evolve (Whenever a creature enters the battlefield under your control, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.) Remove two +1/+1 counters from Experiment One: Regenerate Experiment One. (The next time this creature would be destroyed, instead tap it, remove it from combat, and heal all damage on it.)

Whenever a player casts a spell, you may put a +1/+1 counter on Forgotten Ancient. At the beginning of your upkeep, you may move any number of +1/+1 counters from Forgotten Ancient onto other creatures.

Changeling (This card is every creature type.) Protection from black {2}{G}{G}: Chameleon Colossus gets +X/+X until end of turn, where X is its power.

Whenever a creature you control deals combat damage to a player, you may draw a card. {1}{U}, {T}: Creatures your opponents control attack this turn if able.

Draw a card for each creature target player controls, then draw a card for each creature another target player controls.

Myriad (Whenever this creature attacks, for each opponent other than defending player, you may create a token that's a copy of this creature that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.) Whenever Broodbirth Viper deals combat damage to a player, you may draw a card.

Islandwalk (This creature can't be blocked as long as defending player controls an Island.) Whenever Cold-Eyed Selkie deals combat damage to a player, you may draw that many cards.

When Elvish Visionary enters the battlefield, draw a card.

Flash (You may cast this spell any time you could cast an instant.) Whenever Illusory Ambusher is dealt damage, draw that many cards.

Flying When Mulldrifter enters the battlefield, draw two cards. Evoke {2}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters the battlefield.)

Ninjutsu {1}{U} ({1}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.) Whenever Ninja of the Deep Hours deals combat damage to a player, you may draw a card.

Whenever Ohran Viper deals combat damage to a creature, destroy that creature at end of combat. Whenever Ohran Viper deals combat damage to a player, you may draw a card.

Prime Speaker Zegana enters the battlefield with X +1/+1 counters on it, where X is the greatest power among other creatures you control. When Prime Speaker Zegana enters the battlefield, draw cards equal to its power.

{G}{U}: Target creature can't be blocked this turn. If that creature is a Snake, it gets +2/+2 until end of turn.

{T}: Add {C}. {T}, Sacrifice Command Beacon: Put your commander into your hand from the command zone.

{T}: Add one mana of any color in your commander's color identity.

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

({T}: Add {G}.)

{T}: Add {C}. {T}, Sacrifice a creature: You gain 1 life.

({T}: Add {U}.)

Llanowar Reborn enters the battlefield tapped. {T}: Add {G}. Graft 1 (This land enters the battlefield with a +1/+1 counter on it. Whenever a creature enters the battlefield, you may move a +1/+1 counter from this land onto it.)

Hideaway 4 (When this land enters the battlefield, look at the top four cards of your library, exile one face down, then put the rest on the bottom in a random order.) Mosswort Bridge enters the battlefield tapped. {T}: Add {G}. {G}, {T}: You may play the exiled card without paying its mana cost if creatures you control have total power 10 or greater.

{T}: Add {C}. {G}{U}, {T}: Put a +1/+1 counter on each creature that entered the battlefield this turn.

Oran-Rief, the Vastwood enters the battlefield tapped. {T}: Add {G}. {T}: Put a +1/+1 counter on each green creature that entered the battlefield this turn.

You have no maximum hand size. {T}: Add {C}.

Simic Growth Chamber enters the battlefield tapped. When Simic Growth Chamber enters the battlefield, return a land you control to its owner's hand. {T}: Add {G}{U}.

Simic Guildgate enters the battlefield tapped. {T}: Add {G} or {U}.

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Thornwood Falls enters the battlefield tapped. When Thornwood Falls enters the battlefield, you gain 1 life. {T}: Add {G} or {U}.

Vivid Creek enters the battlefield tapped with two charge counters on it. {T}: Add {U}. {T}, Remove a charge counter from Vivid Creek: Add one mana of any color.

Vivid Grove enters the battlefield tapped with two charge counters on it. {T}: Add {G}. {T}, Remove a charge counter from Vivid Grove: Add one mana of any color.

Create X 1/2 green Spider creature tokens with reach, where X is the number of creatures attacking you. Prevent all combat damage that would be dealt this turn by non-Spider creatures.

Cast this spell only during the declare blockers step. For each creature attacking you or a planeswalker you control, create a token that's a copy of that creature and that's blocking that creature. Exile those tokens at end of combat.

Flash When Plaxmanta enters the battlefield, creatures you control gain shroud until end of turn. (They can't be the targets of spells or abilities.) When Plaxmanta enters the battlefield, sacrifice it unless {G} was spent to cast it.

When Coiling Oracle enters the battlefield, reveal the top card of your library. If it's a land card, put it onto the battlefield. Otherwise, put that card into your hand.

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Sacrifice Sakura-Tribe Elder: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

{T}: Add {G} or {U}. {G}{U}: Simic Keyrune becomes a 2/3 green and blue Crab artifact creature with hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

{1}, {T}: Add {G}{U}.

{T}: Add {C}{C}.

When Solemn Simulacrum enters the battlefield, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle. When Solemn Simulacrum dies, you may draw a card.

You have no maximum hand size. {T}: Add {C}.

When Eternal Witness enters the battlefield, you may return target card from your graveyard to your hand.

When Loaming Shaman enters the battlefield, target player shuffles any number of target cards from their graveyard into their library.

Reach {3}{G}{G}{G}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.) When Arbor Colossus becomes monstrous, destroy target creature with flying an opponent controls.

When Bane of Progress enters the battlefield, destroy all artifacts and enchantments. Put a +1/+1 counter on Bane of Progress for each permanent destroyed this way.

Destroy target permanent.

For each creature your opponents control, create a 4/4 green Phyrexian Beast creature token. Each of those tokens fights a different one of those creatures.

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.) Destroy target artifact or enchantment.

Flash When Mystic Snake enters the battlefield, counter target spell.

Destroy target creature. It can't be regenerated. That creature's controller creates a 3/3 green Frog Lizard creature token.

Until end of turn, target creature loses all abilities and becomes a green Snake with base power and toughness 1/1. Draw a card.

Reach When Stingerfling Spider enters the battlefield, you may destroy target creature with flying.

Flying Whenever Trygon Predator deals combat damage to a player, you may destroy target artifact or enchantment that player controls.

Flash When Caller of the Claw enters the battlefield, create a 2/2 green Bear creature token for each nontoken creature put into your graveyard from the battlefield this turn.

Trample Myriad (Whenever this creature attacks, for each opponent other than defending player, you may create a token that's a copy of this creature that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)

If a noncreature permanent under your control was destroyed this turn by a spell or ability an opponent controlled, you may pay {G} rather than pay this spell's mana cost. Create four 1/1 green Snake creature tokens.

Orochi Hatchery enters the battlefield with X charge counters on it. {5}, {T}: Create a 1/1 green Snake creature token for each charge counter on Orochi Hatchery.

Flying When Patagia Viper enters the battlefield, create two 1/1 green and blue Snake creature tokens. When Patagia Viper enters the battlefield, sacrifice it unless {U} was spent to cast it.