Hi. I run an open table at a local comic book store, and one of my players presented me with this problem: he has a Rod of Quickening, and casts a standard action spell then a quickened spell. If he doesn't move, can he use that move action for a 2nd quickened spell? First I said yes, because a swift action takes less time than a move action. Then I reversed myself because by definition, a swift action is a limited free action, you can only take one per round. But I can't shake the fact that a swift action takes less time than a move action, and the move action is still there to use, but I don't like that a player (or npc) can cast 3 spells. It seems unbalanced. Any thoughts on this?
From the PRD (also in CRB IIRC, but I don't have my copy handy to cite a page number):
Cast a Quickened Spell
You can cast a quickened spell (see the Quicken Spell feat), or any spell whose casting time is designated as a free or swift action, as a swift action. Only one such spell can be cast in any round, and such spells don't count toward your normal limit of one spell per round. Casting a spell as a swift action doesn't incur an attack of opportunity.[Emphasis added]
Your second ruling is correct. He only gets one quickened spell per round.
The rules say explicitly you gain one swift action per turn, any you may never perform more than one, no matter what other actions you have left over.
I agree that this feels counterintuitive and doesn't make sense when you look at each action as a certain expenditure of time.
the solution is simple though. Either you go by the rules and don't let players perform more than one swift action, or you houserule it so they can exchange their move or standard action for another swift action if they so desire. Now since you're already houseruling you may as well also houserule Quicken Spell to say that you may not cast more than one quickened spell per turn.
Often times when a GM makes even a minor adjustment to a basic rule, it comes with a need to also adjust items or abilities that work off this basic rule, to keep the game in balance.
... Now since you're already houseruling you may as well also houserule Quicken Spell to say that you may not cast more than one quickened spell per turn ...
While I agree with the spirit of your post, having only a single Quickened spell per turn is not a house rule. It is spelled out in the core rules. See above.
EDIT: Keep in mind, if you're running an open table at a comic store, and decide to start house ruling mechanics, it'd be wise to be very clear about that to potential players (and probably to have a list of your house rules for them to read).
... Now since you're already houseruling you may as well also houserule Quicken Spell to say that you may not cast more than one quickened spell per turn ...While I agree with the spirit of your post, having only a single Quickened spell per turn is not a house rule. It is spelled out in the core rules. See above.
I was almost certain that this was already a thing but I couldn't find the sentence that makes it explicit, so I went the route I did.