Arcus Acolyte

Outlast was a mechanic remembered mostly for being too passive: the sorcery-speed tap cost meant a creature growing itself couldn't attack that turn, and most of the original crop just sat there converting turns into modest counters, one body at a time. What this Cleric contributes is the ability as an aura rather than as a single instance. It hands outlast to every other counterless creature you control, so a board of small bodies can all spend their taps building at once instead of taking turns. The gating clause is the clever half: the grant extends only to creatures that haven't started growing, so the moment a creature earns a +1/+1 counter it drops off the shared outlast entirely. That's a one-way ratchet rather than a permanent engine; each creature gets exactly its first counter from the borrowed ability, then it's on its own for any further growth (which it no longer has, absent outlast printed on its own card). The effect is self-limiting by design, converting a wide team's first collective push into counters without letting the grant stack redundantly on creatures that already went. The lifelink and reach on a 2/2 are the honest floor, covering the ground and the air while the slow accumulation happens behind it. It's a repair job on a maligned mechanic: outlast always wanted you to go wide, and this is the piece that lets a wide board grow in unison rather than in sequence.