I'm presently running the module "Barrow of the Forgotten King" in one of my RPoL games. My Players have just been introduced to the Tomb Spider – the hard way.
The group's leading Cleric – a priest of Pelor – was bitten by the Tomb Spider. The group finally won the battle, but the priest had been bitten twice and failed one of his Fortitude Saves and so he was poisoned. The group's Cleric of Kord was also bitten, but only once and he made his one Fortitude Save.
The Cleric of Pelor had suffered some decent damage from the two bites, having lost twenty-two (22) hit points out of twenty-seven (27). Once the fight was finished, he chose to cast Cure Moderate Wounds upon himself, thus inflicting himself with another thirteen (13) points of damage, falling to minus eight (-8) hit points.
Of course, everyone started screaming at the Cleric of Kord to do something – no one having rolled a Knowledge check sufficient to know anything significant about Tomb Spiders – and the Cleric of Kord immediately performed a Heal check and poured not one, but two potions of Cure Light Wounds down the fallen Pelorian's throat.
Needless to say, that put our poor Pelorian well below minus ten (-10) hit points. Taps anyone?
Speaking only for myself, of course, as a DM . . . I've found a new favorite among my long list of "friends."