Permeating Mass

Combat between creatures usually asks whose numbers are bigger; this Spirit changes the question to whose creature you keep. Connect in combat and the thing you hit stops being a 6/6 dragon or a 5/5 demon: the copy effect rewrites the entire object into another one of these, identical down to the conversion clause that did the rewriting. It does not knock the threat down to a smaller body, it substitutes one, and the new copy carries the same homogenizing trigger forward to whatever it touches next. Timing is where the rate justifies itself. The trigger fires on combat damage and resolves independently of its source, so when this blocks something lethal and dies to state-based action, the conversion still happens by last known information. That yields a defender able to neutralize creatures arbitrarily larger than itself: block the 6/6, die, and the opponent is left holding a 1/3 where a dragon used to be, the conversion permanent and the mana they spent on the original stranded on a harmless body. Against threats too small to kill it, it becomes a laundering machine, swing after swing folding an opposing board into a row of identical Spirits. The closest structural relative is Lignify: nothing is destroyed by the effect itself, the threat simply stops being one, reduced to a copy that can no longer do anything but reduce others in turn.