Mordenkainen's Polymorph

Flying Fire Breath — When this creature enters, it deals 4 damage to each opponent.

Target creature gets +2/+2 and gains trample until end of turn. Untap it.

T: Add C. XX, T, Sacrifice this land: Create X Treasure tokens.

Psionic Spells — When this creature enters, choose target instant or sorcery card in your graveyard, then roll a d20. 1—9 | You may put that card on top of your library. 10—20 | Return that card to your hand.

This spell can't be countered. Flying, haste R: Inferno of the Star Mounts gets +1/+0 until end of turn. When its power becomes 20 this way, it deals 20 damage to any target.

(T: Add B.)

(T: Add R.)

Vigilance When this creature enters, if an opponent controls more lands than you, search your library for a basic Plains card, put it onto the battlefield tapped, then shuffle.