One thing that always was (is) weird to me is how a monster hits at the same level when they are almost dead... So, any thoughts on having a monster set to disadvantage when their hit points is near or under 20%...?  Good idea?  Stupid?  By the way, I'm fairly new to D&D, so if this has been discussed and dismissed because its silly, apologies.....

teak

It could be a cool concept for a boss monster that is very strong, and you need to chop parts of its body off and thus loses its power,  having a very potent ability attached to each body part.  As a whole probably not a good idea, just because DnD Tends to snow ball pretty hard for a lot of enounters.  Creatures especially get very easy later in levels.  And getting weaker the less hp you have could take away from the fun of the fight.

ive used it to a successful degree, but either using squad based minions that got weaker the less of them were in the squad.  and for bosses that ive explained above.   but most of the time snowballing mechanics are just bad in general.   

Hope this was helpful! 

Quote from RailbladerX >>

It could be a cool concept for a boss monster that is very strong, and you need to chop parts of its body off and thus loses its power,  having a very potent ability attached to each body part.  As a whole probably not a good idea, just because DnD Tends to snow ball pretty hard for a lot of enounters.  Creatures especially get very easy later in levels.  And getting weaker the less hp you have could take away from the fun of the fight.

ive used it to a successful degree, but either using squad based minions that got weaker the less of them were in the squad.  and for bosses that ive explained above.   but most of the time snowballing mechanics are just bad in general.   

Hope this was helpful! 

I'll just mention that swarms tend to do less damage when at/below half health.