Revelsong Horn

The pump is incidental; the tap is the point. A +1/+1 buff for a full mana ranks among the least efficient combat effects ever printed, but the headline number is just the price of admission for the activation cost itself: tap any untapped creature you control. That clause is the product. It is a repeatable, colorless way to turn off one of your own creatures for the turn, which sounds useless until you find the engine that wants it: a permanent that triggers off your creatures becoming tapped, an effect that rewards a tapped board state, or a way to dodge a "must attack" or untapped-check restriction on your own terms. The Horn cares only that the creature is currently untapped, not what it is or whether it could attack, so it converts idle bodies into a resource divorced from combat math. The trade-off is unforgiving: a creature spent tapping the Horn cannot attack, block, or pay a convoke or tap cost elsewhere that turn, making each activation a deliberate sacrifice rather than a free conversion. That narrowness is exactly why it reads as filler to most players, who clock the +1/+1, file it under unplayable combat trick, and move on. It is one of those cheap colorless artifacts built to grease a board-state engine rather than win a fight. Read the second clause first.