So I was reading the boards and realized I wanted to post this as I was trying to remember how they’re defined 🙂  This is copied from a post by Graalx2 who is the main dev posting on the warden boards and other tanking related items.

Originally Posted by Graalx2 View Post

Lets see if I can answer at least some of your questions.

Warden Threat effects stack completely with other Threat effects and with themselves.

The descriptions for the magnitude of a Threat effect are absolute. A Moderate threat increase does the same amount of Threat on a Tier 2 gambit as a Tier 5 Gambit.

The magnitude of threat effects is approximately:
.5x -Slightly increased threat
1x -Moderately increased threat
2x -Increased threat
3x -Greatly increased threat

All Warden Threat over Time effects last 16 seconds with 4 second pulses. The duration is not increased by traits but the magnitude of each pulse is increased by some traits.

Warden heals do increase threat for each pulse of healing, though some monsters care more about healing threat than others.
Couple comments – in threat magnitude the x is a value roughly equal to an autoattack, not a multiplier.  Each ToT pulse has a threat value of  “slightly increase threat” or .5x – so the total threat from a ToT is 2x.