Aran, Elusive Assassin

: Whenever a creature attacks this, put a -1/-1 counter on that creature.
+1: Surveil 2, then mill 1. Each opponent loses 1 life and you gain 1 life.
-X: Exile up to X cards from your graveyard. Choose target creature. For each card exiled this way, put a -1/-1 counter on the chosen creature.