[hxx112]

Don't edit it through notepad.  Use the Skill Manager ingame.

If {(I'm in defiance) AND (target is a boss mob) AND (target's HP % > 95%)}

For this you want to have your action have:

1. PlayerBuffs -> HasBuff for defiance status (91).
   
2. Target -> HPAdvantage > 10
   
3. Target -> HP% > 95
   

If you ever want to use this action below 95% or for trash mobs, you'll have to create another new action without those conditionals, preferably with lower priority on the action list.

Edit: since you are a tank, you can get away with an HPAdvantage smaller than 10. 10 is what I use for my dps classes