I usually carry a couple of teleports and return potions with me at the least. This way if something happens, i.e. I get plagued/poisoned/scourged, etc. I can quaff a return to the healer and try and atleast heal the poison and plague, or keep myself somewhat healed and hope to wait it out. If I am cursed, then I can teleport away from the danger (most times) and wait out the curse and then quaff a return and heal up. While this is not a 100% certainty against these things(no magic rooms, deathtraps, bad teleports, being lagged by said attacker on top of maledictions, etc.) it is some form of insurance against death and does give you somewhat manageable odds against these attacks.