Is Flameskull legal in Standard, Modern, and Commander?

Flameskull is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Historic.

Flameskull

Q: What type of card is Flameskull?

Flameskull is a Creature — Skeleton. Its oracle text reads: "Flying This creature can't block. Rejuvenation — When this creature dies, exile it. If you do, exile the top card of your library. Until the end of your next turn, you may play one of those cards. (If you cast Flameskull this way, you can't play the other card, and vice versa.)"

Creature — Skeleton

$0.36 ↗20 similarCommander, Modern

Flying

This creature can't block.

Rejuvenation — When this creature dies, exile it. If you do, exile the top card of your library. Until the end of your next turn, you may play one of those cards. (If you cast Flameskull this way, you can't play the other card, and vice versa.)

Set Adventures in the Forgotten Realms

Rarity Mythic Rare

Mana Value 3

Artist Xavier Ribeiro

Collector # 143