If something is targeted and then dies on the chain, can you target something new?

Ruling: No, you cannot target something new. Targets are chosen when you play the card. If the original target is not there at resolution, that part of the spell won't have an effect.

Sequence:

• Targets are chosen when you play the card
• Validity of targets is checked again at resolution
• If target is invalid at resolution, that part of the spell has no effect

Nuances:

• Some rare cards make you choose things at resolution, but those are not targets
• For cards that split damage among multiple targets, you choose the targets when played but decide how to split the damage among those targets at resolution