So I was reading through the Kineticist for reasons. And I noticed in the Key Terms and Special Rules sections regarding Overlapping Kinetic Auras:
As normal for duplicate effects, a creature can't be affected by multiple copies of the same effect.
I am not sure if this is a general rule currently in the CRB. But I suspect that it will be in the Remastered Player Core or Gamemaster Core.
I'm also assuming that this would apply to Earth's Bile. Sure you could cast multiple copies of the spell and sustain all of them - but any creature in an overlapping area or otherwise affected by multiple copies of the spell would only take the effect once.
On the other hand, each instance of Earth's Bile is one sustained duration spell effect.
So I was reading through the Kineticist for reasons. And I noticed in the Key Terms and Special Rules sections regarding Overlapping Kinetic Auras:
As normal for duplicate effects, a creature can't be affected by multiple copies of the same effect.I am not sure if this is a general rule currently in the CRB. But I suspect that it will be in the Remastered Player Core or Gamemaster Core.
I'm also assuming that this would apply to Earth's Bile. Sure you could cast multiple copies of the spell and sustain all of them - but any creature in an overlapping area or otherwise affected by multiple copies of the spell would only take the effect once.
It's about this general rule:
When you’re affected by the same thing multiple times, only one instance applies, using the higher level of the effects, or the newer effect if the two are the same level. For example, if you were using mage armor and then cast it again, you’d still benefit from only one casting of that spell. Casting a spell again on the same target might get you a better duration or effect if it were cast at a higher level the second time, but otherwise doing so gives you no advantage.
But I don't think this applies to sustained AoE dmg effects. Just for conditions and other on-going effects that sticks in a target and endures. Damage effect are resolved instantly otherwise you cannot Strike the same creature multiple times because your "reapplying" the effect.
About Earth's Bile sustained duration I think that multiple stances of it can stack due how it's written:
Your apparition is a conduit for the earth’s molten blood, unleashing a devastating burst of lava at your command. When you Cast this Spell, and the first time you Sustain it each round thereafter, choose an area within range. Each creature in the area takes 1d4 fire damage, 1d4 bludgeoning damage, and 1 persistent fire damage (the persistent fire damage is negated on a successful save).
The Earth's Bile dmg effect doesn't endure. What happen it that when you cast or sustain it you repeat its damage effect. So with the exception of persistent fire damage that has its own rules forbidding stack and the duration independent from the spell duration, the effect only occurs specifically when you use the cast/sustain action, damages the target and finishes.
The duration of the spell and the duration of the effects are diferent things here.