I am sure this has been addressed before but anyway...

Before this turn's End Phase begins, if this card was played as a block, you may add it to your staging area.

Does this mean that any time after this card is played it may be put in the staging area or do I have to wait until my opponent states that her End Phase is beginning?

you have to wait untill the end phase of the turn when you clear the card from your card pool

that was a little vague, you have to do it immediately before the end phase

Stamp for teh Ziepnir

Just to clarify...if my opponent states "I end my turn" then I can use the effect? And if my opponent fails a control check then the end phase has already begun and this effect cannot happen?

Doozee said:

Your opponents end phase begins after their combat phase.

This can happen if your opponent "passes" (the official way of saying "i end my turn")

OR

if your opponent fails a form.

There is nothing (in my knowledge) that would prevent you from being able to use that effect.

Even cards like Tenacious just end the combat phase, NOT the turn. Possibly even something in the (new) TR about if a card states "and your turn ends" it means your proceed from combat phase to end phase, not that your turn "instantly ends"

Pull of the Tide might be fast enough, since it can cause an attack to be aborted... not sure though

aslum said:

Nope, wording on PotT is "...their Combat Phase ends".

Which means proceed to end phase.

There is a small window between when the combat phase ends, and when the end phase begins, this is the trigger window for "before your opponents end phase begins"

If it was worded "their turn ends"...then we may have to look for errata/clarification. But as is it should be cut and dry