Does Effortless Concentration count as sustaining a hex for Witch familiar abilities or is this one of those cases where it has to be the Sustain action?
It's just a 0A Sustain, so there's no way for this to be an issue, right?
... You immediately gain the effects of the Sustain action, ...
...wtf, gdi Paizo.
Yeah, that wording is just aggravating. Written as if it's intentionally dodging the actual use of Sustain as a subordinate action.
In this case, I think it has to count as if written to just give you a 0A Sustain action.
Getting the "effects of" Sustain, while not invoking / triggering the named action "Sustain", would actually wreck havoc on spellcasting.
RaW, that would mean getting the effects of spell Sustained mechanics, but you're not actually doing a sustain. Meaning, all the "first time you Sustain each turn" limitations are now dodged.
The only other RaW interpretation of not matching the real "Sustain" would mean Effortless Concentration could never trigger any "when you Sustain" clauses. I cannot even rule it out as invalid due to being mechanically 0-effect. That RaW reading would still allow E.Concentration of adding duration to sustain spells, but never triggering sustain clauses.
Seeing as how that should still get us to consider the "too bad to be true" idea, imo this is a case where the shit wording of Effortless Concentration is a red herring / legacy text.
I'm fully on the side of the ability mechanically providing a 0A Sustain action outright. Any attempt at "only" granting the effects of Sustain would need a hella lot more text to explain wtf that alien idea means.
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Pre-post edit:
Design archeology has paid off, and I've gained 95+% confidence in understanding why Paizo wrote it that way / what was going on inside the dev's head.
The simple version of giving a 0A Sustain would mean the action inherits the [concentrate] trait, and the limitations / hazards of needing that focus.
I'm very certain that "effects of the sustain" wording was an early and flawed attempt at giving you the benefits of a 0A Sustain while *not* inheriting that [concentrate] from it.
Instead, they should have written it with their usual manner of specific override. "You perform a Sustain, but without the [concentrate] trait."
They usually write activities in a "do __ action, but _____ " style, and for good reason.
This is a good question. As Trip.H points out, the wording is ambiguous, so I can't say for sure what the RAW answer is. I can't even say necessarily what the RAI here is, assuming this wasn't just an oversight during the remaster, but I would be irritated if the Witch were given Effortless Concentration in their feat list only to be deprived of what would otherwise be some really obvious synergy. Personally, I absolutely rule that Effortless Concentration counts as Sustaining for the purposes of the Witch's familiar ability, and would continue to do so as a house rule even if the feat was confirmed not to do that RAW. In fact, I'd probably still do that if the RAI was to avoid some edge case or excessively good synergy unless it conclusively broke something at my table (at least, more so than usual whenever The Resentment gets involved).
I could be that Effortless Concentration was deliberately worded such that Witches wouldn't gain the benefits associated with Sustaining without spending the actions...though that would suck.
I think we don't know what the real intention is.
I would however lean towards allowing Effortless concentration to function as though you had sustained.
Yeah, I'm not sure how else to interpret "You immediately gain the effects of the Sustain action" other than to gain all of the effects that the character normally gets for using the Sustain action.
I suppose, because of the rest of that sentence , that it could be interpreted to only extend the duration of the spell and not have any other effects of Sustain action including any 'on Sustain:' effects of the spell. But that is a really restrictive interpretation that I don't think anyone is actually going to run the game with.
So assuming GMs running things in good faith, I would say that a Witch gets all of the benefits of the Sustain action when they use Effortless Concentration. Including triggering their Familiar ability if the effect that they sustain with it would qualify.