Eidolon Harness and Instaneous Effects

[jmclaus]

Does an Eidolon Anchoring Harness prevent instantaneous effects that would force it backs to its plane, such as Banishment, Dismissal, or Blasphemy?

If so, does the Eidolon only have to expend a single use of its master's SLA or does it have to continue to expend a use each round it wants to remain?

[Fuzzy-Wuzzy]

1) Yes.

2) It must expend a use each round that something tries to make it leave. Since an instantaneous effect is only there in one round, it only needs one use per such effect. That is, the thwarted spells don't linger to try again (at least not without the right metamagic).