Hexavus

A counter shuttle in the body of a beater. It lands as a 6/6 flier, a real threat that closes games without any help, but the six +1/+1 counters it hauls in are as much fuel as they are stats. One valve peels a +1/+1 counter off Hexavus to drop a flying counter on another target creature, and this mode needs nothing from the rest of your board: the counters it spends came in on the card itself. The other, and the more interesting of the two, reads "remove a counter," not "remove a +1/+1 counter," so it can strip any counter from another creature you control (a stun counter you would rather clear, an oil counter, a keyword counter that has already done its job) and convert it into raw power here. Both modes cost only generic mana, so the loop is limited by the counters you can find rather than by what you can pay. That is the tell that this is an engine piece as much as a threat: it does a little on its own and a great deal in a shell already treating counters as a currency, ferrying them between bodies and reshaping where the stats and the evasion sit. The flying-counter mode is the cleanest trick in the kit, handing evasion to a ground stack it did nothing to grow: a way to send an army of counter-fed creatures over the top.