can you use your played cards actions on your oponents turn?

eg. use your dimentional rift to wipe the board on your oponents turn?

Absolutely. That's one of the great things about them.

JesseOlivier said:

Yes. The rift would ideally be used during your opponents' story phase, after they have committed. That's when there is the least chance of something popping up before you have your story phase with fresh characters, often running unopposed. And it's a great deterence to playing more things.

There are 2 downsides though: If they don't commit, the story phase ends, and you may have to trigger it at the worst possible time: During your operations phase. The second downside is that you often can't react to them trying to destroy it before you use it.

Being able to figure out what your opponent is capable off, and finding the correct time to use your actions is an important skill. It gives you small edges to be a little more efficient in playing your things - but these add up to claiming a victory.

So, if an action doesn't specify a certain phase or situation, do experiment with the timing. See how it affects the flow of the game.