Avatar of Woe (CMD 73)

Creature — Avatar • Mana cost: {6}{B}{B} • Commander 2011 • Rare

If there are ten or more creature cards total in all graveyards, this spell costs {6} less to cast.
Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
{T}: Destroy target creature. It can't be regenerated.

Illustrated by rk post.