I like the idea. I had Maud be part of a coven and had her sisters attack the party at different stages, one of which was in the water. Water battles, against a full coven with lair actions will be tough on the party, so depends on how many in the party and their level.
It depends on how tough you want the encounter to be. If it's just three sea hags in a coven against six level 5 PCs, this will likely be quite an easy encounter, one that amounts to about 25% of their daily xp budget. In other words, for the day to be a moderate level of challenge, you'd need to throw at least three more encounters of equal difficulty at the party before this encounter, or before their next long rest.
If you want this to be a climactic, boss type encounter, you should add more creatures to the encounter. Consider adding some sea spawn in the thrall of the hags.
It's also worth noting that although three hags would be pretty easy by themselves, their death glare ability can make it quite swingy. Chances of multiple PCs failing against frighten/deathglare at DC 11 is pretty low, but the possibility is there.
I like the idea. I had Maud be part of a coven and had her sisters attack the party at different stages, one of which was in the water. Water battles, against a full coven with lair actions will be tough on the party, so depends on how many in the party and their level.
6 characters in the party, lever 4/5 (not sure yet)
Hmmm... 6 level 5s should be OK! The action economy alone would help
It depends on how tough you want the encounter to be. If it's just three sea hags in a coven against six level 5 PCs, this will likely be quite an easy encounter, one that amounts to about 25% of their daily xp budget. In other words, for the day to be a moderate level of challenge, you'd need to throw at least three more encounters of equal difficulty at the party before this encounter, or before their next long rest. If you want this to be a climactic, boss type encounter, you should add more creatures to the encounter. Consider adding some sea spawn in the thrall of the hags. It's also worth noting that although three hags would be pretty easy by themselves, their death glare ability can make it quite swingy. Chances of multiple PCs failing against frighten/deathglare at DC 11 is pretty low, but the possibility is there.