Mathemagics

Mathemagics is legal in every major constructed format but has no meaningful footprint outside Commander — the effect is simply too slow and too conditional for formats where you rarely cast your commander more than once. In Commander it occupies a narrow but powerful role: pure bulk draw in any deck that recasts its commander several times per game, and a combo finisher in loops that generate unbounded commander-cast triggers. Outside of those shells, a cantrip or a more reliable draw spell will outperform it. Oathbreaker is the one non-Commander format where it could theoretically see play, since the planeswalker-as-commander structure creates similar recasting incentives, but the format's smaller card pool and faster games make it unlikely to matter in practice.