Persistent
General, Upgrade
Cost: As the feat or power being upgraded.
Prerequisites: Any attack action that forces one or more targets to make an initial saving throw to resist
Upgrade: +2 tiers
This +2 upgrade can be applied to any attack action that forces one or more targets to make an initial saving throw to resist. A target that succeeds at its initial saving throw against a persistent effect must reroll the save if it succeeded on any roll other than a natural 20. They take the second roll's result, even if it's better. This doesn't affect saving throws against ongoing effects, only initial saving throws.