Unblinking Observer [Innistrad: Double Feature]

Blast Zone enters the battlefield with a charge counter on it.
{T}: Add {C}.
{X}{X}, {T}: Put X charge counters on Blast Zone.
{3}, {T}, Sacrifice Blast Zone: Destroy each nonland permanent with mana value equal to the number of charge counters on Blast Zone. “Day 77: The homunculus within the crystal continues to mimic my every movement. I wonder what they are writing?” Laboratory notes of Yzlkpk