The Battlemind takes one attack and gets a reprisal. Here is the order of actions that invalidates the second attack:

• The attack is made targetting both the battlemind and the cleric.
• The battlemind triggers lightning rush
• The battlemind makes his attack
• The battlemind takes the attack intended for the cleric.
• The other attack is lost because the battlemind is not longer a valid target. (per the fact that immediate interrupts can invalidate an action if it is no longer a valid action)

I think this has the best support from the RAW that I can find at the moment.

The Battlemind takes one attack and gets a reprisal. Here is the order of actions that invalidates the second attack:

• The attack is made targetting both the battlemind and the cleric.
• The battlemind triggers lightning rush
• The battlemind makes his attack
• The battlemind takes the attack intended for the cleric.
• The other attack is lost because the battlemind is no longer a valid target. (per the fact that immediate interrupts can invalidate an action if it is no longer a valid action)

I think this has the best support from the RAW that I can find at the moment.

It depends on the sequence.

I'll play them out:

• In sequence one the cleric is the first target. The BM triggers lightning rush. Now to make the second attack the yuan-ti must choose a different target and targets the cleric again.

• In sequence two the battle mind is the first target. When the cleric is targeted with the second attack lightning rush can be triggered and the battlemind would the target of both attacks.

Thus it really will depend on how the DM announces the attacks, whether they are seen as granular or seperate attacks (ie capable of being re-targeted midstream) etc.

The Battlemind takes one attack and gets a reprisal. Here is the order of actions that invalidates the second attack:

• The attack is made targetting both the battlemind and the cleric.
• The battlemind triggers lightning rush
• The battlemind makes his attack
• The battlemind takes the attack intended for the cleric.
• The other attack is lost because the battlemind is not longer a valid target. (per the fact that immediate interrupts can invalidate an action if it is no longer a valid action)

I think this has the best support from the RAW that I can find at the moment.