Quick Doom (3.5e Feat)
From D&D Wiki
Quick Doom [Dark]
You have learned to alter the effects of your doom class feature to act faster on your targets.
Prerequisite: Darkness Class Feature, Doom Class Feature, Dark Knight Level 10
Benefit: Your doom ability only takes 1d6+3 rounds to take effect.
Normal: The doom ability normally takes 2d6+3 rounds to take effect.