438a3a28_es___Dungeons_and_Dragons_Wiki__Perk_Benefit
[Perk Name] Cold-Blooded [Pro Perk Benefit] You gain a +4 Bonus to Hide and Move Silently Checks, and you can hide in plain sight as per the Ranger Ability. [Perk Benefit] 
If an enemy uses a thermal scope against you, they do not gain a bonus to attack rolls against you.
CoDnD- Call of Duty 3.5 (3.5e Sourcebook)/Chapter 2: New Rules - Dungeons and Dragons Wiki
Perk Benefit