Flying (This creature can't be blocked except by creatures with flying or reach.)
As long as there are five or more mana values among cards in your graveyard, Aven Heartstabber gets +2/+2 and has
deathtouch (Any amount of damage this deals to a creature is enough to destroy it.).
When Aven Heartstabber dies,
mill (To mill a card, a player puts the top card of their library into their graveyard.) two cards, then draw a card.