When a player chooses an illegal target for a spell (e.g., targeting a unit in base when the spell can only target units on battlefield), what happens? Does only the target get canceled while the spell remains pending, or does the entire action get rewound?

Ruling: When a player selects an illegal target for a spell, the entire action is rewound and cancelled. The spell returns to the zone it was played from (hand), costs are undone (runes unexhausted, recycled cards returned from under deck), and the player is not forced to replay the spell even if legal targets exist.

Sequence:

• Illegal target selection prevents the spell from finalizing
• All actions taken during the play process are undone
• The spell returns to hand
• Runes are unexhausted
• Any recycled cards are returned from under the deck
• The action is cancelled

Nuances:

• Even if legal targets exist, the player is not forced to choose them and replay the spell after the rewind
• This is different from reflexive triggers (like Falling Star/Rain) which work differently
• In tournament play at High OPL, this would result in a general error warning