It's come up in several forums, blogs and emails I get from people. Energy Draining is one of the deadliest forms of non-kill (outright at least) attack forms a monster possesses. As a Referee, I see it as a debilitating attack form that should be rightly feared (and one that there are few avenues of recourse for). I've heard from others that simply slam the ability as 'nerfing' a character, 'crippling' a character, that it's a Referee's way to 'beat' a party that is too powerful for him to handle (I think this one comes from someone disgruntled with his Referee, but I'm not sure as it's not from anyone in my own group).
Energy Draining has been a staple of D&D and it's clones and is something a select few creatures in Onn possess. I'm curious now what others think of the ability and how they handle it.