Barriers block him from being able to devour allies. So does bless. Black Beast was intentionally patched to dispel before attempting to devour after barrier was changed to block devour attempts so this wouldn’t be an issue. Any (already generally not very good) strategy that relies on him devouring allies to boost is completely stalled when you get an impervious summon. Don’t know why he needed another set of tools he is incompatible with.
I still think this guy should dispel then curse before devouring so his spell could at least be consistent. Yeah, that means he wouldn’t be able to target himself, but seriously.