Let's say you use your move action to move a few squares, downgrade your standard action to a move action, and, with your move action, move half your speed and trigger an effect that grants you the staggered condition (in this case a homebrew persistent AoE spell, but it could be anything).
Would your action be stopped and your turn ended, as you are only able to take one move action a turn now? I don't see anything clear on this in the rules, and I could - as it stands - see it being ruled either way in a game.
Thoughts? Thanks.
The rule set doesn't do much to explain interrupted action, imo. Whenever logically possible, I let actions resolve. Meaning, for example, if someone is swinging their sword and something happens, the momentum from that action is still in play. But, if this logically doesn't make sense, such as an immediate action that interrupts the attack altogether, it stops cold.
So, if the nature of your homebrew effect is to stop people cold in their tracks, then I would say their turn ends immediately. Otherwise, if possible, let them hobble those last few steps since they still have actionable energy left in them, again, depending on how your homebrew effect is written.
I'm comfortable making a ruling in any given situation, but I'd like to know if there is a rules as written interpretation.
Ignoring the homebrew spell, let's just say someone readies an action that ends up dealing enough damage to stagger an opponent. What happens?
The homebrew spell is, rulewise, the same as this situation. It's an AoE that can cause the staggered condition on a failed save.
I rule that anything which changes your number of actions such as staggered takes effect during your next turn. Makes for much better pace of play than any other solution I've found.
In your example of a readied action, that is something I would say prevents the character from taking their action. If you play out the movie in your head, you've basically been hit by the ACME 1 TON weight. It doesn't make sense to keep kicking like you were prior to that happening.
This was discussed at great length about a month ago. If you gain the staggered condition and you've already made a move or a standard action, you are done for the round, even if that means aborting what you're doing right now.
If you become staggered while making a full attack, you stop. If you become staggered while in the second half of a double-move, you stop. If you become staggered while charging, you stop.
TL;DR
The ruling was effectively that you should act as if the staggered condition was acquired at the start of your turn.
Staggered limits you to a move OR standard. You can't do both.