Can I Star Cross a unit that Leblanc is trying to copy with her legend ability, and does the reflection token have temporary?

Mistake on retarget and added niche case

Yes to both. You can Star-Cross a unit LeBlanc is copying, and the Reflection token does have Temporary. Star-Crossing the copy target: Deceiver's copy instruction is a reflexive trigger that goes on the chain after the Reflection token enters — that's a Closed State window, so you can react with Star-Crossed ([Reaction], 3E). If you bounce the unit she intended to copy, that unit is no longer at the battlefield, so the copy effect fails for it. You can also Star-Cross the Reflection token itself; it's returned to hand and then ceases to exist since tokens can't exist in hand. Temporary: Yes — Deceiver's own reflexive trigger reads "It becomes a copy of another unit there. Give it [Temporary]." The Temporary is granted directly by the legend ability, not copied from the target, so the token has it no matter what it copies and will die at the next beginning phase (Rule 816). This is confirmed by the official Zilean/Deceiver clarification, which notes Deceiver "gives the tokens Temporary." Niche case: If Leblanc Legend has no other units present, and you react before a target was declared by the reflexive trigger, the Leblanc player receives a 0m reflection without temporary. This because the reflexive trigger can not finalize and is removed from the chain as there are no legal targets left to copy. FAQ #11306; Deceiver card text.