Inaccurate?

Master?s Wil

( Elder Evils, p. 13)

[Vile]

The elder evil you serve is fickle in its rewards and punishments.

Prerequisite

Chosen of Evil (EE) (or undead type) , Evil Brand (FCI) ,

Benefit

As an immediate action, you can beseech the elder evil for assistance. Roll 1d20. If the result of the die roll is an odd number, you gain a +8 bonus on one attack roll, saving throw, ability check, or skill check for 1 round. If the result is even, you take 1 point of damage for each Hit Die or character level you possess.

You must make the decision to use this ability before making an attack roll, save, or check.