level draining is indeed considered by bioware to be too cheesy...you only get gram at near end of tob...you see, its really rather simple...my infamous cast g deathblow and fire frag grenade, area effect deathblow kills a entire room of improved mind flayers in one single shot, most boiware created cre files for monsters have about level 4-8, just their stats makes them nasty...g deathblow, cloudkill and death spell, all really popular, takes advantage of that, a lot of really nasty fodder are low level but uses high stats to look nasty but are very vulnerable to spells that bypass magic resistance, like level drain, and attacks at point of most vulnerability, level number...
the most powerful level draining item in the game is dagger life stealer, which is 4 level drain,
if you think valen is bad, try sk ing her to assassin fighter, and go past 4 million xp and she becomes a matriarch vampire...