Power Matrix

Repeatable combat boosters usually carry a mana cost on the activation to throttle them; this one asks for nothing past the four mana to deploy it, and after that the only resource it spends is its own tap. That tap is the entire balance lever. Because the effect needs the artifact untapped, you normally buff one creature per turn, not pile the bonus across an attacking team or feed multiple activations into a single threat unless you find a way to untap it. The +1/+1 is the part that actually matters to that restriction: the keywords it grants (flying, first strike, trample) are redundant on any creature that already has them, so stacking would do nothing anyway, but each tap delivers a fresh stat bump and a fresh choice of recipient, and the tap caps both at one per turn. The keyword package is the telling combination. It is not assembled to win a damage race so much as to declare that one creature, this turn, cannot be blocked at a profit: flying forces the question of whether anything can even stand in front of it, trample punishes a chump block, and first strike protects the attacker whether it lands in the air or on the ground. Colorless and cheap to install, it turns whatever happens to be on the table into an evasive finisher, which is why permanents that hand out evasion at no recurring cost stay rare; the design is generous enough that the per-turn tap is the only thing keeping it honest.