Riddleform

In Commander, Riddleform slots cleanly into spellslinger decks — Niv-Mizzet, Parun, Melek, Izzet Paragon, and similar commanders cast enough noncreature spells per turn cycle to animate it reliably, and a 3/3 flier that appears and disappears is harder to profitably block than a permanent creature. In competitive 60-card formats like Modern and Legacy, Riddleform is too slow and too conditional — dedicated tempo and control shells have no interest in a threat that requires a noncreature spell each turn just to attack. Pioneer is the friendliest 60-card home, where spellslinger and prowess-adjacent strategies exist and the power ceiling is lower, but even there it sits outside the mainstream. Treat Riddleform as a Commander card with a noncreature-spell payoff role; anywhere else it's an experiment.