In the Daravel Ancestral Tomb, there is a skeleton that casts spells which damage skills. The only way to fix this is to leave the dungeon and visit a shrine which can restore attributes. This is a terrible thing because it means you will no longer be able to hit the enemy with weapons or cast spells which can damage the enemy after several seconds of fighting it. This is bad enough, but there is another, tanky skeleton who will get between you and the mage skeleton, and a greater bonewalker which willsap your strength and keep you from being able to dodge the spells. Oh, and of course, the skeleton that casts the "you lose" spells also has a stick which paralizes, just in case the player manages to deal with the greater bonewalker.
Damaging skills is not something that should happen in any Elder Scrolls game, but in Morrowind especially, since your ability to even do damage in the first place is based almost entirely on your skills. The enemy would make for a much more compelling fight if it instead drained agility and willpower, making it harder, but not impossible, to hit with weapons and to cast spells.