Rehearsed Debater

Most spell-matters payoffs count spells cast: cheap threats that grow whenever you point a cantrip at anything, or a permanent, or nowhere in particular. This one narrows the trigger to a specific kind of spell, the pump or burn or removal that already wants to target a creature, and turns that overlap into a body that spikes exactly when your combat spells are on the stack. The design tension it resolves is that spells-matter creatures usually reward you for casting cards you were going to cast anyway, which makes them passive; here the payoff and the interactive spell arrive in the same window, so a burn spell aimed at their blocker also swings your own math. The vigilance is doing quiet work in that plan, keeping the growing attacker back on defense without asking you to choose between the +1/+1 and a safe board. What it wants is a critical mass of targeted instants and sorceries already in the list, folding the incidental buff into plays you were making anyway rather than one that asks you to warp a deck around triggering it.