Sydria the Elder is located at 2260, -1310, 365 (beginning of the valley that leads to Crystallos).
In order to buy spells from Sydria the Elder, you must have ally faction with "Crusaders of Veeshan"; completed the full "Beyond the Barrier" task; and have kill credits for the Brood Mother Visziaj and Kerafyrm raid events in Crystallos.
https://everquest.allakhazam.com/db/npc.html?id=27590
only posting because it took me almost 30 mins to locate where this was obtained after turning in all the Glowing Prismatic Rune and Whirring Clockwork runes