What a fun batch of baddies! There's some excellent ideas for abilities in here I'll definitely pull from for future encounters. Looking forward to the full adventure. Here's a few thoughts:
- Given the narrative of the Hammer of Blood, I wonder if Vaalyun's Replenishment ability should only be usable if he's attacked someone with the hammer that turn, as opposed to any damage dealt. Might add another interesting tactical layer to how he fights and how the players approach him as well. This isn't something I think is needed, just a light suggestion for your consideration.
- The bonus damage of The Blood Hammer might not come up in some encounters, but could get crazy in others if the wielder gets their hand on a minion squad. Perhaps the bonus should be a pool that you can save up to spend on a strike rather than something that lasts the encounter? It'd still scale well into the 5th level upgrade, since you can gift the pool to allies.