I'm digging through the three new classes here at the moment and I'd like to specifically offer some feedback of Summoner. I think this one in particular needs some more time cooking. And it's mostly the core talent that's the problem.
The way this reads is that the summon has a 4d pool that drops to 0 then always, arbitrarily, and immediately, goes back to full. This is not related to its harm or whether it's on the plane etc.
Unless I've seriously misread it, in which case that's a different issue but still an issue with the text... That's... really extremely disconnected from any sort of narrative. And almost strictly worse than a normal animal companion in most cases when it's not rolling that maximum. It seems that the writers have made a lot of effort to make the fiction tie into the mechanics in a better way with a lot of the OG classes (Psion for instance is a genius change to how its resources operate), but this one strikes me as a complete miss both mechanically and narratively. Why is it randomly losing power if that doesn't banish it? Why does it recover infinitely at 0? Etc. The design just doesn't make any narrative sense.
It also reads like this pool is specifically for directing the creature. Which naturally implies the summon doesn't act without being directed manually by the summoner. The talent is a bit wishy-washy on its specifics, so I'm not sure that's actually the intent, but I also can't help but notice this class does literally nothing in combat other than this so I'm guessing it is. In a funny way, the CE has fixed my problem with the warlock - a lack of actual magic without taking 'multiclass' talents - in exchange for doing the same thing to the summoner.
You can get up to three of these eidolons as well, but it's not actually clear from the text whether that gives you three power pools or if they share one power pool that's related to you. It cannot recover naturally, which also leads to situations where it'll be at 1d at the start of 'adventuring days' completely unlike any other class resource in the game.
That's only viewing it in a vaccum too. Keeping in mind as well, a wizard or anyone else with normal Potent casting can according to the Summoning Spells part of spellcasting, definitively make creatures with equal 4d power pools, except they can do it multiple times in the same combat, all independantly able to act for however many times the wizard can cast a potent spell. Those creatures cannot take any hits, true, but the eidolon can only take three before its completely out of action, while a wizard could theoretically summon a 4d pool creature every single turn for three turns at level 2 and make the summoner look like a chump, mechanically. Meanwhile the Ranger gets to probably very effectively use weaponry while his pet also at the same time gets 3d attacks of its own. Technically speaking Summoner doesn't even actually have any sort of spellcasting touchstones so it also cannot benefit from Ritual summons, which a wizard can summon with some prep-time for 8d creatures.
Both rangers and conjuror wizards can easily also outperform this class by simple action-economy, even in a freeform initiative system, if the above assumption that they can do things like shoot while the pet also attacks, meanwhile a summoner is forced to direct the pet, which also makes having three useless except for versatility while the wizard straight gets versatility and power.
If you ask me what the solution to all of that is, I think it's pretty obvious the pool should be a per-session resource pool for summoning, rather than a power pool for summoning and pet actions. The pets should just have 3d on anything within their vantage and 1d on anything else, more like an animal companion. This also makes having three of them pretty meaningful. It can't be overstated how little this class does in combat except for those pets though. If the idea is that the summoner should be pushing themselves to bolster their pets, then maybe they should have an in-baked ability to assist the pets magically, maybe with a push? A little side ability like the Witch's Ritualist sub-talent bonus where the Summoner gets free access to actual summoning touchstones instead of just only planar travel as a side-ability and +1d boost to rituals related to conjuration would go a decent way to rounding out their magical feel too. Any summoner worth their salt is obviously going to want to perform a Ritual of summoning at some point for a big nasty demon or something like that for a climactic moment, and this as written cannot even do that.