Ulamog, the Defiler

When you cast this spell, target opponent
exiles the top half of their library, rounded up.

Ward—Sacrifice two permanents.
Ulamog, the Defiler enters with a number of
+1/+1 counters on it equal to the greatest
mana value among cards in exile.

Ulamog has annihilator X, where X is the
number of +1/+1 counters on it.