Well, first, I'd try with an ophidian slayer weapon or reptile super slayer.

Second, do your armor have the good resists for ophids?

Third, do you carry enough greater cure potions with you?

Fourth, if you can afford it, buy orange petals making you resistant to poison.

Five, find someone to go hunt there with you and cross-heal

Last, if your skills aren't in the 90ish, I wouldn't bother trying to go there. Knight Errant and Avengers are just too hard for you.

If you are a mage, just cast EV, run there, drop the EV, run back. Rince and repeat until the shamans are done dispelling your EVs or are dead.