Riverfall Mimic

Change the text of target spell or permanent by replacing all instances of one color word with another. Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

Wither (This deals damage to creatures in the form of -1/-1 counters.) 1G: This creature gets +2/+2 until end of turn. Activate only once each turn.

Trample Tap an untapped red creature you control other than this creature: This creature gets +X/+0 until end of turn, where X is the power of the creature tapped this way.

Enchant creature As long as enchanted creature is black, it gets +1/+1 and has deathtouch. (Any amount of damage it deals to a creature is enough to destroy that creature.) As long as enchanted creature is green, it gets +1/+1 and all creatures able to block it do so.

As this creature enters, choose an opponent. This creature enters with a -1/-1 counter on it for each creature that player controls.

Flying U: Target permanent becomes blue in addition to its other colors until end of turn.

Other blue creatures you control get +1/+1. Other red creatures you control get +1/+1. U/RU/RU/RU/R: You may put a blue or red creature card from your hand onto the battlefield.

Chroma — Reveal any number of cards in your hand. You gain 2 life for each green mana symbol in those cards' mana costs.