What specifically are you confused about?

A Player Action Window is simply the point in the game where players are allowed to use non-Response triggered effects. You know, event cards or other card abilities that have a phase name or "Any Phase" in bold at the beginning of it. So the "player actions aspect of the challenge phase" is just when during a challenge you can use an effect that starts with "Challenges" or "Any Phase."

If it helps, think of the "anatomy of a challenge" described above as:

1. Attacker names the challenge type and kneels attacking characters.

---> Players get to "do stuff."

2. Attacker assigns stealth, then defender kneels defending characters.

---> Players get to "do stuff."

3. Resolve the challenge.

I am mostly confused on the fact of when do you discard event cards and other cards such as the great keep is it at the end of each round or do you discard them at the end of the challenge as one time use cards

Event cards go to the discard pile after all responses to them - if any, there are often none - are played. So almost immediately.

Why are you discarding the Great Keep? Characters, attachments and locations don't leave play unless something specifically makes them leave play.

Generally, every effect you trigger (events, character abilities, etc.), the process looks like this:

1. Initiate/trigger the effect.

2. Opportunity to cancel it or play saves against it

3. Resolve the effect

4. Passive effects

5. Responses

6. Move everything that died, was discarded, etc. goes to the dead pile, discard pile, etc.

Then move on to the next triggered effect. So you see it moves pretty quick.

He means Borderland Keep.

so i can have a character card and location card with the limited keyword on the field at the same time, they just have to be played in different marshalling phases? what about two locations? they just have to be played in different rounds? lol im just starting as well..

so theres a plot card in the core deck that states the player with the most cards must discard cards until they only have 4 remaining. are character cards discarded or do they go to the dead pile?

and also is there a limit to cards you can have in play at once? ive never seen anything say specifically but there is a diagram in the rule book that has 8 spaces so ive always been unsure...

You would be better off posting in a new post

a) LIMITED - this is a restriction on playing cards during a round - each player can only "play" one limited card per round - NB There is no limit on the number of cards that you can "put into play"

b) All cards discarded from your hand go to the discard pile - unless there is a stated replacement effect on the card text

c) There are no limits to the number of cards you can have in play

thank you so much ive never posted on a forum before lol