You will need to complete that temple quest with your Paladin if you want to get the crusade trait. It's been a while, but I believe that is the scroll of galian, and it is not deep in the dungeon. It is :
Spoiler coming
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Go left from the pool through to what looks like a kitchen. Don't go down the elevator, go further left to a small area with a few skeletons and a couple of chests - from memory the scroll is in there.
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