Death Sense

Death Sense is a Fallout Tactics perk available only to deathclaws.

Effects
You have developed superior senses. The perk gives you a +20% bonus to Perception while in the dark and a +25% bonus to detecting enemies using the Sneak skill.

In reality the perk increases the Perception of a deathclaw by 2 permanently. You just have to be a deathclaw to take this perk.