Poison of the Hydra

Poison of the Hydra creates interesting interactions with the spell Poison.

Immunity Stripping

This ability adds a 1d4+1 poison damage dot to the poison spell and removes poison Immunity as is stated in the ability description. Most immunity removals that typically require either 2 ticks of a DoT, with the first removing the immunity but doing no damage and the second dealing full damage, or casting two separate abilities with the first being a primer for the second to do full damage. Poison does not have this issue. The constitution damage, or the save against, applies first and removes poison immunity allowing the initial instance of poison damage on cast to go through even on naturally immune targets.

Meta Magics

Poison is a unique spell in that it does not deal direct damage on it's own, but is still able to be maximized, empowered, and intensified. Seemingly, Poison's constitution damage scales with spell power of some sort (more testing is needed to identify which), as running maximize and empower allow for constitution damage that far exceeds the 1-10 expected range. This unique characteristic allows Poison of the Hydra to gain the benefits of these metamagics as well, boosting the DoT damage from this passive.

Spell Saves and Spell Resistance

Poison of the Hydra's poison DoT will still apply to a target even if they are naturally immune to constitution damage (such as undead), are stat guarded (such as bosses that cannot take more than 10 points of any one stat damage type), or if the target makes it's fortitude save to negate the original spell effects. The save from poison damage appears to be a separate roll from the initial save from the constitution damage.

However, if an enemy possesses spell resistance, and the caster of Poison fails their spell penetration check, NONE of the effects of Poison or poison of the hydra will be applied including the poison immunity stripping.