I could definately see it as being "per-encounter." The way I would like to see it is that the player gets the most basic abilities as "per-encounter." Ex: Wizard gets "Magic Missle," or a Rouge gets something like an "Epic Dodge" some many times per encounter. I could see the more extensive abilities as "per-day." In the example of wizards something like "Gate" or "Meteor" should only be cast once per day. In the example of the rouge maybe something like an assassin's "Death Attack"
As for the barbarians the rage ability could become toggleable during an encounter? I think it would be interesting if a number of abilities could only be activated per day and under the event that rage was toggled on. My vision of Rage would provide more serious bonuses and penalties but have no after effects. Example: Maybe he gets +4 str, +6 con +2 will saves +4 attack damage -4 attack bonus -4 ac and provide access to a number of "rage only abilities". This way, chosing to activate rage is a tactical decision. Sure, it lets you do a ton of damage and gives you access to these abilities, but if these abilities can only be activated "per day" you're going to see a natural disposition to using it every encounter because you might not have your "per-day" abilities accessible. And if you don't have your abilities accessible you can see that there would be a disposition to using a toggleable ability like Rage every fight. It would be great to use it in instances where you're fighting Xvarts, or Gibberlings or Bandits. You'd clear those in less than thirty seconds. Or in fights with a lot of wizards / clerics, the will save bonus could prove more useful than the -4 is hurtful. But in instances where there are a lot of fighters, the barbarian might need the ability to hit and their ac bonus.
tl;dr: Thoughts on a togglable "Rage" ability and having "Per-Day" abilities only usable when Rage is activated?
