I've grown fondness for Philippa Eilhart during the story of Witcher 2 and so naturally I want to help her or at least encounter her in Witcher 3.
Spoilers, beware!
I'm at the point where Radovid asks me to find Philippa Eilhart. I've recovered the crystal, killed the mage hunters outside her hideout, and now face the decision whether to give it to Radovid. Judging by the journal entry and Geralt's monologue, there should be an option to ask Triss or some other sorceress to study it and hopefully provide clues regarding Philippa's whereabouts, yet Triss has already departed to Kaer Morhen after helped her save those in hiding, and the game doesn't leave any obvious clues as to whom to take it to. Does it mean I've lost the option to find her without Radovid? Can I find Philippa if I give the crystal to Radovid and still save her? (I've been wanting to save her and murder that sucker with Dijkstra.) Can I find her if I withhold the crystal?
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I've seen a short video of a fight with Philippa which can end by Geralt saving her and then allowing Triss to help her (they go somewhere through a portal), so it should be possible. The only thing I don't know is whether the game is so badly made that this option is no more without any indication whatsoever or whether it's the result of another quest later.
Unfortunately, I've done a lot of quests since helping Triss to escape so I'm asking this before I revert to an old save. Thanks!
Update:
I've found another video of the quest in question (Redania's Most Wanted) and just as I suspected, the game gives Geralt the option to take the crystal to Triss before Radovid so I indeed missed it (I think it's wrong not to give even the slightest warning). However, it doesn't show whether the quest ends at that point or not. If it does, the fight and subsequent story I've mentioned clearly take place later on.
Update 2:
I've finally found another video which shows that despite talking to Triss and then Radovid, the quest ends there, hence the events depicted in the first video must take place later on. Whether the presence of Triss during this quest affects the next one is still uncertain, though. I hope I'll be able to see that. 🙂
Yes, this much effort for one fictive Philippa Eilhart. I really like her, lol.
Best Answer
I was in the same predicament (Triss left Novigrad already, and Yennifer's Last Wish quest also done), but was able to find a solution.
Basically, you sit on the quest until the main story takes you to Kaer Morhren, after which you can speak to Yennifer and have her look at and hold onto the crystal. Then talk to Radovid to complete the quest.