Skirvak, Legion of Liches

Trample, lifelink, menace
Whenever one or more creature cards are put into a graveyard from anywhere, amass 1 (Put a +1/+1 counter on an Army you control. If you don't control one, create a 0/0 black Zombie Army creature token first.)
As long as there are 10 or more cards in your graveyard, Skirvak, Legion of Liches is an army in addition to it's other types.