While def cool and something I will be taking advantage of going forward, I really think the Dungeon Journal should make this clear. There is no reasonable expectation a player would read,"Mistcaller wants to play Dodge Ball and throws an anima ball at players, inflicting 3603848 Nature damage to all enemies in a line."and conclude this would do damage to the clones or the vulpin. Maybe if it said targets instead of enemies but even then most people assume enemy abilities cannot friendly fire without it being obvious and part of an encounter's core mechanics, not some optional min-maxing. I would add a second line stating the potential to friendly fire very clearly.
The biggest improvement to this dungeon would be to delete it from the game. Seriously, it's obnoxious. Everything about its design is insufferable. A maze, a "guessing game" boss, and a drop to a pool that's juuust tiny enough that there's the feasibility of someone hitting the branch instead of the water and breaking their legs. Not to mention that one tiny "bridge" of roots that has a sneaky fall-off point. Literally watched someone fall right down it yesterday and I don't blame them because I almost didn't see it myself.
The issue with this mechanic is it isn't noted anywhere. It has worked this way since beta when m+ testing started. The issue is the Dungeon Journal does NOT reflect this and says the balls only damage enemies (from the boss' perspective). This is different from similar mechanics like say the hook on Stitchflesh which specifies the first "target" hit.