While carrying a Survivor you benefit from the following effects:

Decreases Wiggle effects, which cause you to strafe sideways, by 75 percent.
Increases Wiggle duration by 4/8/12 percent.

Grants the Undetectable status effect after gaining Bloodlust Tier 1.  The status effect is removed once you lose Bloodlust.

Gain 50percent more Bloodpoints for actions in the Hunter Category.

You recuperate faster from missed attacks made with your main weapon.
Reduces the Cool-down of missed Basic Attacks by 20/25/30 percent.

As soon as an exit gate is opened, Blood Warden is activated.  The auras of any Survivors located within Exit areas are revealed to you.  Once per match, hooking a Survivor while Blood Warden is active calls upon The Entity to block both Exits for all Survivors for 60 seconds.