Ankle Biter

Prerequisite: Goblin race
Benefit: You gain a +1 feat bonus to damage rolls against creatures larger than you. This bonus increases to +2 at 11th level and to +3 at 21st level.
    Also, when you score a critical hit against a creature larger than you, the creature takes 1d6 extra damage.

Published in Into the Unknown: The Dungeon Survival Handbook, page(s) 38.