Phase keyword abilities such as the one on The Palantir (
Shadow:Remove
![2 [2]](https://lotrtcgdb.com/forums/Smileys/classic/2.png)
to...) may be used as many times as you can pay the cost. In the case of palantir, that cost is removing 2 twilight. The only other limitation on phase keyword abilities are those explicit in the ability's own text, ex.
Trust Me As You Once Did and its limit of +3. And even then, that limit is only for that individual card. You can get +3 strength off of each
TMAYOD you exert Gandalf to use. Hope that helps. But yeah, Carl is right. "At the start of each skirmish..." And other abilities that trigger in the same way ("when the fellowship moves to this site", etc" and are performed once.