So the reality of what you would be doing to 3.5/p is:

  1. Add a concentration action, similar to a swift action, where each character gets one concentration action a round maximum and they can do it alongside their various move/attack/cast/fullround/fivefootstep actions
  2. Explain the concentration action and what it does for spells that will be limited to concentration.
  3. Go through thousands of spells and figure out which ones to alter from "duration: 1 round per level" to 'duration: concentration (max 1 round per level)" or similar.



The end result, instead of the casters putting tens of buff spells on themselves and their party before combat begins, they will end up limited to one buff spell. Their usefulness as party-buffers is now all but gone unless you figure out how to make 'buff other spells' not concentration gated - perhaps by moving the concentration to the person being buffed instead of the spellcaster?

Ultimately, i'd want to know what the non spell casters get to do with their concentration actions that they don't need? I'd like to see you add something for the fighters and thieves and monks to do with concentration actions.