Can I take one of my hits and (via Mangler) turn it into a crit, then use Bossk's ability to turn the crit back into two hits, effectively getting an extra damage?

Can I take one of my hits and (via Mangler) turn it into a crit, then use Bossk's ability to turn the crit back into two hits, effectively getting an extra damage?

If you hit, yes, I don't see why this wouldn't work.

Yep.
Bossk's ability triggers farther down the path than Mangler's.

Ya, the ability triggers only if the attack hit. The mangler flips hit to crit after you rolled and modified dice.

Yes, so...

Roll attack dice

convert 1 boom to a kaboom

(do any other attack dice modifications)

defender rolls defense dice

(do any defense dice modifications)

cancel dice and determine if attack "hits"

Bossk converts a remaining kaboom (if there is one) to 2 booms

Thank you all.