There was a lot of magic on Buffy, however there were a few spells that went way beyond the standard locator spell.

In Season 2 Willow, even after being injured in her first attempt, performed the spell to re-in-soul Angel. In Season 4 the Scoobies combined their essences with Buffy that made her into a “Super Buffy” giving her the opportunity to kill Adam. In Season 6 at the very beginning of the season Willow, Anya, Tara, and Xander used the Urn of Osiris to bring Buffy back from the dead, and all the way to Season 7 when Willow used the magic of the scythe to turn all potential slayers into the real thing.

I would say that in their own right, each of the spells altered the course of the show permanently.

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