Borealis, The Arbiter

Borealis costs {x} less to cast, where {x} is half of your board's total power.
Hex-Proof (This card cannot be destroyed by spells)
Annihilator 6
Trample
Vigilance
When Borealis deals combat damage, he puts 5 +1/+1 counters amongst your creatures.
{5}{r}{r}: Borealis, the Arbiter exiles a target creature. Borealis gains +1/+1 counters equal to the creature's power.