For me, PoE's problem on the per-encounter front is that most of them aren't powerful enough relative to their respective levels/enemy defenses.
Assuming a reasonably competent player, there's a reason a D&D magic user (0-2e anyway) only gets to cast a couple of spells. Sleep wins an encounter immediately 99% of the time. Now I'm very mucfh for giving that more mage something else to do besides throw darts as a general rule but at least this is spectacular. "fuck we got ambushed by 9 orcs" "Mage: got it". Nothing in PoE is anywhere near that powerful.
It's partly due the crazy (bad, IMO) stat system where your abilities are fed by like 3 difference stats at least, if not more. So you usually wind up not getting the major impact on some front (whether it's damage, less duration, aoe). But part of it is that a level 1 character in PoE is pretty freaking stout and combat works in such a way that even say 12 seconds of knocking someone down (and I don't think you ever get anything nearly that dramatic; most of the longer debuffs are lower duration), it takes that long for the party to work through the other one or two other bags of hitpoints next to him, oh and there's two shooty bags of hit points behind those guys. More likely your AoE knockdown gets you like 6-9 seconds of respite, which is nice but not exactly "mage just saved our asses". And the damage on a lot of stuff. . I m ean it's just low relative to how many defenses you need to penetrate. It makes for a somewhat stately real time combat which is better than e.g. Ultima VII's. But in PoE 1 it meant that the addtional balance layer of Per Rest was really pretty unsatisfying.
Some abilities work based on accumulated resource (Discipline, Arcane, etc just like the Cipher), so it will be interesting to see if they do anything interesting on the resource generation front. I assume other powers will just be straight up per encounter/modal/passive/etc. Should be a much better system (although I do wish they would junk the current stat system and start over).