Invasion of Karsus // Refraction Elemental

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.) When this Siege enters, up to two target creatures each get +2/+0 and gain vigilance and haste until end of turn.

Creatures you control get +2/+1 until end of turn.

Trample Whenever this creature attacks a battle, it gets +1/+1 until end of turn.

(T: Add B.)

When this creature enters, choose one — • This creature gains haste until end of turn. • Destroy target artifact or enchantment.

Reach This creature has indestructible as long as it attacked a battle this turn.

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.) When this Siege enters, return target nonbattle permanent card from your graveyard to the battlefield.

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for 1 or one mana of that creature's color.) Flying, vigilance When this creature enters, put a flying counter on each creature that convoked it.