Oathsteel Harbinger

Trample, Hexproof
Metalcraft — As long as you control 3 or
more Artifacts, Oathsteel Harbinger has {t}: Put X +1/+1 counters on Oathsteel Harbinger where X is Oathsteel Harbingers toughness plus the number of Artifacts and Lands you control.
The arrival is the beginning of the end.