Each time a Survivor other than yourself is killed or sacrificed, Sole Survivor gains 1 Token, up to a maximum of 3 Tokens:

Each Token grants a stack-able radius of 20/22/24 metres within which the Killer is unable to read your Aura, up to a maximum of 60/66/72 metres.
Once you are the last Survivor standing, you benefit from the following effects:

Increases your Repair speed of Generators by +75 percent.
Increases your Opening speed of the Exit Gates and the Hatch by +50 percent.
Increases the odds of becoming the Killers initial Obsession by +100 percent.

The Killer can only be obsessed with Survivor at a time.

Press and hold the Active Ability button for 6/5/4 seconds while standing beside a dropped Pallet to reset it to its upright position.

Grants the ability to see the Auras of all dropped but not yet destroyed Pallets in the environment.

Increases your Action speeds in Repairing, Healing, Sabotaging, Unhooking, Vaulting, Cleansing, Blessing, Opening, and Unlocking by 3/6/9 percent when in the Injured State.

When injured, healing another Survivor without using a Med-Kit also heals you with a Conversion rate of 40/45/50 percent.