Quote Originally Posted by Borror0 View Post
I'm not sure why you think it's preferable to the current version of Heroic Surge. While on the plus side it does require more active thinking to use, it's a much greater "easy button" than Heroic Surge would represent (and you took issue with that).

In terms of usability, it fails in that the casual players has to know of its existence and use it appropriately. In that sense, it's an added level of complexity at the early levels of the game when the contrary should be happening (ie the learning curve would be improved by being less abrupt). It also fails if the situation occur more often than once per 5 minutes, though that is probably a minor point compared to the previous two.
So change it to auto apply at certain hp threshold. In fact, IWD II had the following feat:

HEROIC INSPIRATION:
When things look grim, your character rises to the occasion.
Prerequisite: At least one level of barbarian, bard or paladin
Benefit: When the character drops below 50% hit points, he or she gains a +1 bonus to hit, damage, and saving throws.

So apply heroic surge when reaching below (20hps+5*level) and for 15 seconds after gaining hps over the threshold. At lower levels, you will be constantly protected from CC, resulting in new players very seldomly being effected, and once they get hit once or twice, becoming immune. At level 20, it will kick in once under 120 hps, enough to normally take care of the cause. The hps threshold is low enough to be effective yet not be exploitive that someone would stay at 100hps to constantly be immune to CC.

Tweak numbers as needed of course, just my rough draft.