Dire Upgrade

Prerequisite(s): Diehard, Endurance, at least one feat with the word "Dire" in its name
Benefit(s): Choose a feat that you possess that contains the word "Dire" in its name; each hitpoint threshold for that feat's effect is reduced by 40.
For example, the Dire Offense feat would normally provide you with a +4 circumstance bonus on attack rolls while your missing hitpoint total is greater than 80, a +6 circumstance bonus on attack rolls while your missing hitpoint total is greater than 120, a +8 circumstance bonus on attack rolls while your missing hitpoint total is greater than 160, etc. However, if you were to apply the effect of this feat to Dire Offense, you would gain a +4 circumstance bonus on attack rolls while your missing hitpoint total is greater than 40 (instead of 80), a +6 circumstance bonus on attack rolls while your missing hitpoint total is greater than 80 (instead of 120), a +8 circumstance bonus on attack rolls while your missing hitpoint total is greater than 120 (instead of 160), etc.
Special: You can gain this feat multiple times; each time you do so, you must choose a different feat that contains the word "Dire" in its name.