The Habs are trying to deal a goalie not get one back...

habs havee indeed been tyrying to rid themselves of a goalie.. basically all year

so TheNSFBBs is just some genius on the toilet that has never seen any habs games, nor read any habs articles.

Easy decline by the habs they arent using a retention spot for a bunch of junk

This trade indeed makes no sense for Montreal. That said, the Habs might very well accept a goalie against the one they ship out. Hughes is looking to get rid of a goalie that he believes has value. Accepting one that has no value (or even negative value) might very well be the necessary lubricant for shipping out one of our goalies (against a better return, of course). Then, Ranta, Campbell, or whoever, can go drive the zamboni in the ECHL for all we care.

For the Habs, this is basically Allen and about $1M cap space (this year only) for a 3rd, 4th and 5th. Maybe that undervalues Allen. Could certainly amend the picks or swap with prospects. Maybe Allen can block to SJS, maybe MTL-CAR don’t want to work together. Idk maybe send him the EDM for better picks/prospects and an offsetting salary (Foegele?)? Who do you think wants Allen?
Anyway, outline of the deal could work by replacing MTL/Allen with BUF/Comrie.
And by the way, we’re all toilet geniuses here.

The worst part of this trade from my point of view is Hughes using his last retention slot for virtually no value. With the plethora of vets we'd be opened to trade at the deadline, we need to keep that slot open for a deal that would bring significant value. If any GM would be ready to take Allen against 3-4-5 leaving 1M in cap space on the table, I think Hugues would have pulled the trigger already.

Yeah you (and another guy) are probably right this does not maximize the return on the final retention slot given MTL are sellers. But this is just the salary-match/filler portion so there are workarounds. SJS-CAR could route Barabanov through another team for the 5th.
The main part of the trade is CAR-SJS; I only involved a third team to get SJS a decent goalie replacement and balance salaries.

montreal is out

Yes Montreal try to reduce the number of goaltender they have with the big club but they could have help in AHL to help dobes at Laval. So accepting an goaltender back from an Allen trade could be acceptable for the right price and the right guys.