So, Fatigue! Keep it light weight.
Fatigue is basically just a separate Wounds counter. When your Fatigue + Wounds equals or exceeds your Fortitude, you're out of action due to exhaustion, even if you haven't taken enough Wounds to defeat you yet.
Invoking a "Zap! This happens!" power is normally free. These are powers that ARE NOT CUMULATIVE. So it wouldn't matter if you spent all day doing it... you won't really accomplish that much more.
Invoking a "Big Effect!" power costs 1 Fatigue. These are powers that require a lot of time... hm.
Maybe like this... all powers need to be described in such a fashion that invoking it is just a single action, but the number rolled is the really important bit. I do not want powers where you can reasonably go, "Oh, just a d2 or d4 of this is fine! Just use it again whenever the old use wears off!" Powers that HAVE to be like that maybe could incur 1 Fatigue instead.
Ideally, powers like Command the Waters and Bless Plants should not have cumulative effect. If you reroll, you just get the best result. So you CAN spend a few minutes and automatically get the highest possible roll... but that's all you can do. Even that sounds a little unbalanced... hm.
How about time limits? Powers are Instant (takes a round), Quick (takes a few minutes) or Slow (takes hours). Ideally, with powers like Command Waters and Bless Plants, there should be a big difference in effect if you choose to take longer. ie- it takes a round to bless a small plant, a few minutes to affect a big tree or a garden and hours to bless a huge field.
Ties are boring. They delay the game. So, to help make sure that tied rolls don't make things dull, there are some ways of resolving them.
1: mutual hurt. You both score a success against each other, representing an exchange of harm. This brings things closer to a resolution and definitely helps the side with a larger number of combatants.
2: concession. If your foe demands a mutual hurt, the defender can substitute a concession, where he takes a -1 penalty to his next action by giving way in some fashion. In a real fight, this often means retreating or giving up your next attack.
3: follow-up. Either side can declare a follow-up maneuver. This is basically a "maneuver for advantage" check that you get to squeeze in as consolation for rolling a tie. It can be any reasonable competition but it has to use a different stat & skill than the first test. So you could try a kick (Athletics + Brawl vs same), etc.
Possibly replace "Cleverness" with "Cunning". Has about the same meaning and has fewer syllables.
Skills
Brawling (Brawn): unarmed combat.
Charm (Cunning): ingratiating yourself with others. Covers seduction and flattery.
Melee (Athletics/Brawn): fighting with lethal weapons.
Ranged (Athletics): fighting with ranged weapons.
Possibly add an "Esoterica" spell skill that adds bonuses to the others. Sort of like the Deryni game's skill that represented ancient secrets.
I was thinking about the magic system for the Age of Powers again... here's my thought...
Each mage has a magic rating of Xd6, with the higher X is, the more powerful they are. They get to allocate up to that many dice to the various Powers as they learn to draw magic from them.
So if you have 4d6 Sun magic, 3d6 Moon magic and 5d6 Wellspring, you can maintain up to 4/3/5 points worth of that magic simultaneously... but if you concentrate all on one power, it takes longer but you can add 1/2 of your other powers to it.
So that 4d6 Sun magic could become 4d6+8d6/2 = 8d6 if you throw your full concentration in it.