Gotcha. Trickster does seem like an interesting option though yeah I agree that it might be difficult to do RP-wise. Doesn't seem like the rogue options fit super well with Berath.
Alright as I consider more about this and went through another character creation session (I'm so indecisive), I pretty much just clicked through every single class and subclass and my eye was piqued by the synergy both RP and mechanics-wise for Helwalker/Berath. Obviously it'd change continuity with class but I'd think of it as the Watcher "dying" at Caed Nua (for the death-rite ceremony) and then when Berath puts him back into his body, he's changed a bit.
Assuming this combo would play something like early on summoning the greatsword/using touch of rot to be a damage based off-tank. Then later on be able to dump some of the damaging priest spells to nuke a bit, not being super worried if I hit myself with a bit of the AoE since it would help build wounds. Then if I feel like I'm getting too much in danger, I'd have MIG powered healing spells plus can always dump wounds into monk abilities to rubberband myself back? This would fit my idea of using a great sword and heavy armor still.
Not sure where to put my stats though since it seems very MAD or at least not one that could be dumped fully.
Something like this maybe:
12 MIG
12 CON
14 DEX
16 PER
16 INT
8 RES
The low RES seems ehh with wounds effect but wearing heavy armor should offset that a bit? And then MIG seems low but assuming Wounds bonus offsets - though I'm not sure if it would be better to pump it higher get even MORE damage.