Spells and incantations - Most voted

Traditional Irish Curse

May the curse of Mary Malone and her nine blind illegitimate children chase you so far over the hills of Damnation that the Lord himself can't find you with a telescope.

Spells and incantations Irish

Traditional Wexford Curse

May the grass grow at your door and the fox build his nest on your hearthstone.
May the light fade from your eyes, so you never see what you love.
May your own blood rise against you, and the sweetest drink you...

Spells and incantations British