If you can't target any opponent with Rakdos Firewheeler's ability, the ability doesn't go on the stack. You can't have it deal 2 damage to any creature or planeswalker. On the other hand, if you do choose two legal targets but either target is illegal when the ability tries to resolve, the other is still affected as appropriate.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.
Slawomir Maniak2024-01-12
