Multiple ki powers at once

[Efrate]

Question about the unchained monk. Is it possible to activate multiple ki powers at once with the same swift, like elemental fury and the extra attack during a flurry for one swift?

If not, would it break too much if I allowed it? You pay all ki costs still so you are kind of novaing but ripping through your meagre ki pool in a few rounds.

[Psyren]

You can't use one swift action to activate multiple abilities that require it, no. Getting an extra swift action is also very hard to do, and this is intentional. For example, the Corset of Delicate Moves (https://www.aonprd.com/MagicWondrousDisplay.aspx?FinalName=Corset%20of%20 Delicate%20Moves) item does this but has heavy restrictions.

How "broken" multiple swifts in a round are depends heavily on your group's power level. You could probably allow them to buy or craft a Greater Corset that is usable 1/encounter or even 1/round instead of 1/day.

EDIT: Another way to get an extra swift action is using the Ready standard action. You can ready a swift, however it can only activate when it's not your turn, which restricts the types of swift actions you can ready.