Example: This time, the fighter makes two of his initial saves against the spider venom, so he only has one dose active in his body. He fails his save on his turn. On the spiders’s turn, two of them bite him, and he fails both saves, which increases the duration to 8 rounds and the DC to 18, just as if he had failed all three saves in the same round.
Ok, but what if he is bitten by one of those three spiders next turn. Does he take the damage again?
Poison (Ex) Bite—injury; save Fort DC 14; frequency 1/round for 4 rounds; effect 1d2 Strength damage; cure 1 save.
The DC and duration go up, but the damage dose not.
The frequency is 1/round = he takes damage once a round till he saves against the DC.
3 Spider Hit (DC14,1 fail, 2 save) duration 4 rounds
Fighter (DC14,1 fail) 1d2 Str Damage
2 Spiders Hit (DC14, 2 fail) duration 7 rounds (3 left, 2+2 new)
Fighter (DC 18, 1 fail) 1d2 Str Damage (Damage dose not go up)
1 Spider Hit (DC 14, 1 save) duration 6 rounds (duration dose not go up)
Fighter (DC18, 1 save) poison cured