there is no way Dumi doesn't have Arizona on his no trade list

He waives knowing he will be flipped to a contender

Not sure the return for Dump at 50% is worth the opportunity cost. Arizona has other players they can use that retention slot for, Ghost notably. There are also other players/teams out there that would probably garner better return than this deal for Dumo (Kane/Toews, for example) and would cost fewer real dollars. A deal like this probably goes to the wire with all the sellers trying to put together three-way deals.

Mmm you're probably in the range, but I still think it can be beaten.