Icy Clutch of Stygia

Heroic Tier
Prerequisite: Tiefling
Benefit: Whenever an enemy successfully saves against ongoing damage that you imposed, that enemy takes cold damage equal to your Charisma or Intelligence modifier.

The cold damage inceases to 5 + your Charisma or Intelligence modifier at 11th level and 10 + your Charisma or Intelligence modifier at 21st level.

Published in Player's Handbook Races: Tiefling, page(s) 26.