This necklace will let you gate to the Plane of Knowledge. Each cast consumes a single Quintessence of Knowledge which is made with Alchemy. The reagents cost about 1/3 less to make than gate potions and they stack to 100.
Melee classes will like this item since the reagents are cheaper than gate potions, and any class may find a “second” bind point useful, so this quest is worth considering for anyone.
You can make a copy of this spreadsheet to track your progress through the three talismans. The first one only has five charges, the second one has fifteen, but the third and final one has unlimited charges.