Syndalhairn is a magical spear, found in an underwater cave off of the coast of the Forest Of Ancients by Karna, at the instruction of her warlock teacher, Gwyndolyn.
Syndalhairn is what is known as a Hexblade; an enchanted weapon imbued with the power to grant its wielder magic abilities. These weapons are bonded to the very soul of their owner, and are intertwined with their life force, turning them into Warlocks (people with no natural gift of magic that draw their power from elsewhere).