While island hopping with a party which included Astarion I had lots of issues keeping him alive
some islands were fairly large and had no water animation at all on the center region of the island but i could not find anywhere that didn't give me the wet debuff
i apologize if this isn't a technical problem, but it seems to be, if i don't see water it shouldn't kill me
i ended up using my other characters to scout for wet and not wet areas first before moving astarion, sometimes it didn't even make sense because i could move him 2 meters and be safe, and 2 more meters and be dead still in what appears to be a water free area of the island
if this is not a glitch, my recommendation is to include a possible red indicator or some such if controlling astarion on when he would be entering moving water
last note: following he is smart enough not to kill himself, but this does not seem to help when you need to jump from area to area
