As a rogue with max 121 unbuffed fire resist, I haven't died to Rag once yet and I haven't sucked any healers dry. Get the rogues greater fire protection potions. Drink one before the fight starts so the cooldown on it will be ready for when you have to drink another because you will have to drink another. Back out of range of the AoE when knockback is announced. If your main tank did NOT resist the knockback, wait a bit before re-engaging. If the main tank DID resist knockback, you can go in fighting. Remember to use feint. When your first greater fire protection potion gets burned through, drink another. If you get hurt, back away and bandage. It's actually quite easy to live through if you pay attention and watch your aggro.
Edit: "Fire" does not equal "first".
Edit: "Fire" does not equal "first".
Intolerant monkey.