Cirilla, Mage Unleashed

Cirilla costs {x} less to cast, where X is the number
of Humans you control. First Strike, Vigilance, Protection from monocolored Instants and
Sorceries.
Whenever a you control creature dies, you get an experience counter. Cirilla gets +1/+1 for each experience counter you have.
Wrath - Spend 7 Experience counters: Destroy
each creature you don't control.