I added your spell to my server Sandy and i spend some time to test it.
For me, the spell need some tweak, as well as your quest. You actually use "quest::selfcast", im wondering if this dont restrict the spell to the NPC, whatever the target spell is, im not a dev, im not sure about this, maybe a dev could answer, but this could be why your are not dispelled, because the NPC SELFCAST.
For me, you should use "quest::castspell(id,spellid);", the problem now would be your spell is "Point Blank AE" and im not 100% sure the spell will work as wanted, the solution would be to set the spell target to "Target Based AE".
This way, Terris Thule cast spell on a PC, the PC is used as Target Based AE and raid party is dispelled, as AE range is very large it would be same thing as having Terris casting spell on herself.
I have never play PoP, so i dont how encounter really work, but this way could be a way to bypass your problem.
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