Marvin, Murderous Mimic

Ability-stealing has a long design lineage, but almost every prior version copied whole creatures or borrowed keyword abilities off the top. This one narrows the theft to a single, underexploited category: activated abilities, and specifically the ones you already control. That constraint is what makes the two-mana body defensible. A 2/2 that inherits every tap-to-do-something and every mana-cost activation from your other creatures does nothing on an empty battlefield; it is a battery that only charges when your other bodies are doing the work. The clause excluding creatures with its own name is the tell that the designers were thinking about a specific abuse case: line up a mana dork, a sacrifice outlet, or a repeatable pinger, and this becomes a second copy of each, at the cost of hanging the whole plan on one fragile toy. The strategic axis it opens is redundancy without duplication: instead of drawing multiples of the creature whose activation you want, you draw the creature and this, and now you have two mana taps, two sacrifice buttons, two of whatever the ability is. It rewards a battlefield built out of small, individually modest activated abilities rather than one big engine, because it multiplies the parts you have rather than upgrading any single one. The friction is entirely in fragility and setup; the payoff is a toolbox that reconfigures itself around whatever else survives.