Can anyone please tell me what the ruling is for the following, and why?

Black Panther is on 10HP (that is, he has taken 1 damage). He uses Wakanda Forever and the last upgrade is the Vibranium Suit.

The card text says: " Special (attack) : Move 1 damage from your hero to an enemy. (2 damage instead if this is the final step of this sequence)."

What happens?

1. He does not have 2HP to move so the action fails.

2. He heals 1 damage (the max) and deals 1 damage.

3. He heals 1 damage and deals 2 damage (pretty sure it isn't this one, but for completeness...)

4. Something else.

Thanks.

EDIT: I've now received email confirmation from Caleb that it's #2.