Menace
Modular 2 (This creature enters with two +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)
Whenever you cast a spell other than your first spell each turn, put a +1/+1 counter on this creature.
(18/06/2021)
Arcbound Tracker will consider spells you cast before it was on the battlefield. For example, if Arcbound Tracker is the first spell you cast in a turn, each subsequent spell you cast after it's on the battlefield will cause the last ability to trigger.
(18/06/2021)
If this creature gets enough -1/-1 counters put on it to cause it to go to the graveyard, modular will put a number of +1/+1 counters on the target artifact creature equal to the number of +1/+1 counters on this creature before it left the battlefield.
