It takes a couple of bolts to kill a prong, so you can count on getting hit if you don't get two bolts in before the first round, I think I've splorked them a couple of times with a bolt, but that would have to be a good roll without a save.
Irap is a good area for mage style runs, chicks always boltsplork, and lizards have a decent chance of it, while dodos are a nice two bolt mob that doesn't hit like a prong can. Necrop has a lot of good thin ethers too, and nymphs in Tony's are splorkable with a bolt.
In the end, you're probably better off killing smaller mobs that you don't have to take a round of hits from, lower per kill xp will be more than made up by longer runs from not constantly having to heal.
Depending when you play (for availability of other players), the single fastest way you can run xp is by teaming up with a thief of levels equivalent to your own, if you're not set on soloing.