Hangover is essentially Hades version of poison, and is the main mechanic for the god Dionysus. Different sources of Hangover will inflict differing amounts of damage-per-tick (i.e. hangover inflicted by your special is more damaging than hangover inflicted by your dash), and it can stack up to 5 times. The part I'm unclear on, since the game doesn't explain it, is how hangover effects stack when that damage is coming from multiple sources.
I can think of a few different ways it could work, with the two most likely candidates being that either the oldest stack is overwritten, or the lowest damage stack is overridden. If it's the former, then combining multiple sources of hangover can actually be really bad, since using anything but your highest damage Hangover attack would actually be lowering your Hangover damage-per-tick.
This would be easy to test if you actually could actually use boons against Skelly, but you can't, so the only option is testing in combat. Considering how fast past the game is, that's a task easier said than done.
How do different sources of Hangover stack?