Colette's prompt on a Coryphee

[Falconrider]

Does this sound legal?  

 

Colette using Prompt to trigger final act on a Coryphee but prior to the end of the turn the Coryphee has been sacrificed to summon a Coryphee Duet.  I would think yes though my opinion is biased as it's something i plan to try out, though i can see the potential for it to cause some players to call foul. 

[The Godlyness]

Not foul. And if it makes them feel better the corpyhee was sacrificed before the end of the turn.

[zdendalini]

good combo, I have to say

[Sholto]

I used it in a game and it was a nice trick, but not OP.