First off, since the Fatigue system will allow characters to take extra actions during combat, it makes getting rid of the existing Action Point system a necessity. Secondly, since it will make characters able to do a bit more during combat than they could with those Action Point rules, you'll need to make sure that enemies are a bit more buffed up than they usually are. Start by using the updated monster stats from the Monster Manual 3 and the Essentials Monster Vault. They're a bit tougher than the original wave of monster design. Lastly, if you normally use Fortune Cards in your game, you should probably forgo using them, at least while you initially try out this system.
Before I go any further, please note that these rules have not yet been playtested. If you decide to try this system out, please leave a comment letting me know how it worked out and any changes that you made to make it work better. OK, on with the show...
The threshold statistic is an abstraction of how far your character can push themselves before becoming fatigued. Your threshold is equal to half of your number of healing surges per day, rounded down. Effects such as rituals or magic items that give you temporary or conditional healing surges do not affect your threshold. Only effects such as feats or class features that give you permanent healing surges affect threshold.
You gain fatigue points by taking extra actions in combat. You may take any number of extra actions during your turn in combat, but for each action you take beyond your normal allotment, you gain one fatigue point as soon as the action is resolved.
The Fatigued Condition
- You take a -2 to all Strength, Dexterity, and Constitution-based skill checks.
- You are slowed.
- Any effect that would cause you to gain the slowed condition instead immobilizes you.
- Any effect that would cause you to gain the dazed condition instead gives you the stunned condition.
- Any effect that would cause you to gain the stunned condition instead knocks you unconscious.
- If you take a standard action (including using a standard action to perform a lesser action), you grant combat advantage until the beginning of your next turn and you gain a fatigue point.
At the end of a short rest, you reduce your fatigue point total by 1. At the end of an extended rest, you reduce your fatigue point total a number of points equal to your threshold. You may not reduce fatigue points by more than your threshold in a 24-hour period, even if you take successive short rests.
Any time a character would spend a healing surge to regain hit points, they may instead choose to loose 1 fatigue point. Effects that grant additional hit points of healing do not affect the number of fatigue points lost. A character spending healing surges to reduce fatigue points may reduce their them by more than their threshold.
Fatigue from Other Sources (Optional)
At the DM's discretion, other powers or effects may deal fatigue points. In general, an effect should never deal more than 1 fatigue point at a time, and should deal it as a replacement to something else the power does, not in addition to it.
Monsters and Fatigue (Optional)
To even out the score, you can let the PCs opponents take advantage of this system as well. Minions and regular creatures of level 3 or lower do not have threshold scores. Regular creatures of level 4 or higher have a threshold score equal to half their level, rounded down. Elite creatures of any level have a threshold of half their level, rounded down, plus two. Solo creatures of any level have a threshold score of half their level, rounded down, plus five.