Recently I played a game of the quest Weather Hills (The Lost Realm) and had a rather interesting situation arise.

I played the Galadriel Ally and then had Cold from Angmar and Biting Wind appear during staging. After placing 2 damage tokens on her I realised this meant due to Cold from Angmar that her text box was now effectively blank meaning she would not leave play at the end of the round. She then stayed in play until I advanced to the next quest stage contributing 3 willpower to questing over several turns instead of one. Not a rules question or answer per say but an interesting situation I thought I would share.

The core set Gandalf ally would similarly have the same effect if damaged and would stay in play until Cold from Angmar leaves play (advancing to the next quest stage) allowing you to get far more bang for your buck with him.

Exposed Ridge is a great card to keep active if you have "bounce-in" allies like Gandalf. At the end of the refresh phase, which occurs before the end of the round (

The end of the round comes after the end of the refresh phase. Everything that triggers at the end of the refresh phase triggers before the end of the round. The end of the round and the beginning of the round can be thought of like book ends to the game round and each phase therein.

) you deal a damage to your ally, so at the end of the round he won't leave play.