This one is related to #1075 "Wisps don't attack properly". Jeff indeed made possible for wisps to damage the player (including the expected lightning balls from the wisp at the forest building) and fixed the always-hostile problem, but there're 3 things quite different from the original games with current (03-2016) snapshots and I thought they could be worth another look after all this time:
1) Wave/sparkling effects wisps do when they attack are missing
2) Fire fields and ashes they leave behind when on rampage are also missing
3) It seems their main attack is summoning VERY nasty fellas of the likes of dragons and liches, which indeed makes for their lack of serious punch when doing damage... hell, I actually like it! But... I couldn't see 'em summoning ANYTHING on original BG. Could it be a bug in the original game preventing them from using some of their actual powers?
from our old SF tracker https://sourceforge.net/p/exult/bugs/1943/