Iron-Shield Elf

Iron-Shield Elf is legal across the competitive formats but won't see play in Modern, Pioneer, or Legacy — Ward 2 on a two-mana instant is simply too slow and narrow against the removal density in those environments. Standard is the one constructed exception where protecting a key creature for a turn might matter enough to consider it, though it's still competing against cheaper and more versatile protection spells. Commander is where Iron-Shield Elf actually finds a home: multiplayer slows the game down enough that a well-timed Ward counter can protect a combo piece or a commander through a critical turn, and the instant speed means you can hold up mana without telegraphing the play.