Arcbound Tracker is a common Artifact Creature — Dog card from Jumpstart: Historic Horizons (J21), collector number 409.
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.