Eldritch Evolution

Offspring 2 (You may pay an additional 2 as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.) Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, Mice you control get +1/+0 until end of turn.

+2: Ugin deals 3 damage to any target. −X: Exile each permanent with mana value X or less that's one or more colors. −10: You gain 7 life, draw seven cards, then put up to seven permanent cards from your hand onto the battlefield.

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "T, Sacrifice this token: Add one mana of any color.")

This land enters tapped. Whenever a Mountain you control enters, if you control at least five other Mountains, you may have this land deal 3 damage to any target. T: Add R.

Look at the top three cards of your library. Put one of them into your hand, put one of them on the bottom of your library, and exile one of them. You may play the exiled card this turn.

Devoid (This card has no color.) Kicker 1C (You may pay an additional 1C as you cast this spell.) When you cast this spell, search your library for a land card, put it onto the battlefield, then shuffle. When you cast this spell, if it was kicked, exile target land.

Offspring 2 (You may pay an additional 2 as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.) At the beginning of combat on your turn, target Mouse you control gains your choice of double strike or trample until end of turn.

Haste Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.) Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, exile the top card of your library. Until end of turn, you may play that card.