At 4th level, when a vindicator confirms a critical hit, he may sacrifice a prepared 1st-level spell or available 1st-level spell slot to invoke doom upon the target as an immediate action (using the vindicator's caster level). The save DC is increased by +2 if his weapon has a ×3 damage multiplier, or by +4 if it is ×4. The vindicator can also use this ability in response to being critically hit, even if the attack incapacitates or kills the vindicator.
