Lukara, Mad Necromancer

Whenever you discard a card, 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.)
{t}: You may discard a card. If you do, you mill X,
where X is equal to the converted mana cost of
the discarded card. (To mill a card, a player puts the
top card of their library into their graveyard.)