TL:DR - Cant move while using ability bound left click as Drain life, during the first phase of the boss fight
So I played through the base story of the game as an Acolyte, and went down the Lich path. I enjoyed very much playing as a sort of “Plague Bearer” style DoT character, and although slow to beat this boss I did so.
However, I am using the Drain Life skill as my basic attack (and I use the ability on R, and then set my left click to be R/Move). I have no difficulty moving and playing with this ability on my left click, and had a great time playing… UNTIL I met this boss. While up on his platform, I assume because this skill (Drain Life) is based on ground targeting rather than enemy targeting, I could not move properly. Instead of moving to avoid the high damage skills my character would start to drain the floor regardless of where my mouse was pointed, including back towards the opposite end of the enclosed area for this boss rather than nearby to him. I was occasionally able to move by targeting my mouse VERY far down away from the boss, but the majority of the time I could not move at all and had to change my key bindings to fight the boss.
Normally if I wanted to target the ground like that, after having played most of the game with my left click as a basic skill (I think the first one I used was called “rip blood” but I might have that name wrong, and then I used Drain Life for the rest of the game once I unlocked it), I would need to use the shift key to attack while not moving. I had no other issues at all with movement until this final story boss.
I know this probably isn’t an issue every player will have, but I hope the devs will look into how targeting works in his closed off first phase, because it made the game literally unplayable as I kept getting 1shot by the boss from being unable to move and that was beyond frustrating. If they are going to allow for you to change the left click binding, and you use a skill that is ground targeted rather than enemy targeted, this needs to be improved in this area of the map or it will likely cause some issues. I’m unaware if any other classes will have this issue with other abilities or if other players regularly use the left click binding to put a “basic” spell on left click/move, but it very much interfered with my ability to play the boss how I played the rest of the game.
Once I changed my key bindings, I had to relearn them somewhat as well as the boss mechanics to win and I eventually did, but it was far more frustrating than it should have been given that I had no issues doing this until that point.