If a star-crossed targets A and B, and another one is played in reaction targeting B and C, is the second star-crossed on the chain still played even though one of the original targets is gone?

Yes, the second Star-Crossed remains on the chain and will resolve.

Whether a spell remains on the chain after its targets change depends on whether those targets have become completely illegal (moved to a non-board zone) or merely invalid (no longer meet the targeting requirements but are still on the board). However, in your specific scenario, the second Star-Crossed is simply a separate spell played in response to the first, and the legality of the first spell does not prevent the second from existing on the chain.

Here is the breakdown of why this works:

1. Separate Targeting Relationships

When you play the first Star-Crossed (targeting A and B), it establishes a targeting relationship. When you play the second Star-Crossed (targeting B and C), it establishes a completely separate, independent targeting relationship.

2. Resolution Order (LIFO)

Because of the "Last-In, First-Out" (LIFO) nature of the chain, the second Star-Crossed (targeting B and C) will resolve first.

• If B is still on the board when the second Star-Crossed resolves, it will successfully return B and C to their owners' hands.
• If B is no longer on the board (e.g., if it was somehow removed before the second one resolves), the second Star-Crossed will still resolve; however, it will only affect the remaining valid target (C), per Rule 359.3.e.8.

3. Independence of Spells

Even if the first Star-Crossed were to become "invalid" (e.g., if Target A were removed), this has no mechanical impact on the validity of the second Star-Crossed. A spell does not "fizzle" or leave the chain simply because another spell targeting the same object has changed in status.

Summary of the Sequence:

1. Player 1 plays Star-Crossed (A, B): Placed on the chain.
2. Player 2 plays Star-Crossed (B, C): Placed on the chain on top of the first.
3. Resolution: The second Star-Crossed resolves first. It returns B and C to hands (if they are still legal targets).
4. Resolution: The first Star-Crossed then resolves. If A is still on the board, it will return A to its owner's hand. If B is already gone, the first Star-Crossed will resolve only for Target A (Rule 359.3.e.8).

Important Note: As per Rule 355.10, you must have both targets (a friendly unit and an enemy unit) present on the battlefield at the moment you play Star-Crossed to initiate the spell. Once placed on the chain, if one target becomes unavailable, the spell proceeds to resolve using any remaining valid targets.