The Too Faced Chocolate Bar palette is up on Debenhams' site, and it does say it's exclusive to them. It's £45. There are a couple of other new Too Faced items on there too.
I was able to get £15 off of it, as TopCashBack now have the option of getting your cashback paid into a Debenhams Gift Card. You request it and they send you a gift card with no money on it. You then go onto the TCB site and enter the giftcard number, to confirm you've received it, and they then put the money onto the card. Good idea really, as it saves the card getting intercepted in the post with money on it.