So I took my mage friend out to the withered area (no, not to leech, you XP whores), and had her set up behind me off from the lugians. Near some Drudges, Tumeroks, and Banderlings, in fact.
The idea was for her to cast extinguish spells on me (as well as heal), while I fought the usually-avoided spellcasting mobs.
Seems like a decent enough idea, especially since she's such a solitary player that she wouldn't ordinarily get to go out there.
Not so good results, although we lagged out and lost the connection.
Here's the thing -- those extinguish spells take a LOT of mana. Like 280 without Mana Conversion. She figured it was costing about 200 per spell. So we had to let them debuff me to a huge degree before pulling the trigger on casting the spell. Oh, and since she's not killing, the XP is basically halved (although I'm just not enough of a whore to care).
Humph. Another good idea down the drain. :-(