Calciderm

In Commander, Calciderm is a fringe include at best — four turns is usually enough time for opponents to build a board that makes a lone 5/5 irrelevant, and white has access to creatures that provide lasting value rather than ticking down. Legacy and Vintage have the raw power to make a turn-two 5/5 with shroud feel threatening, but neither format is looking for a vanilla beatstick when faster, more resilient threats exist. Modern is where Calciderm had its most credible moment, as a difficult-to-answer body for aggressive white shells, but the format's power creep has long since passed it by. Across every legal format, the shroud clause that protects it from targeted removal also means you can't save it with flicker effects or proliferate tricks — what you see is what you get, for exactly four turns.