The Ancient One possessed the ability to manipulate the forces of magic for a vast number of effects and was able to tap into extra-dimensional energy by invoking entities or objects of power, existing in dimensions tangential to those of the Earth, through the recitation of spells.
The Ancient One also possessed a variety of mystical objects, such as the Book of the Vishanti, the Orb, Amulet, and Eye of Agamotto, and devices gathered throughout his lifetime.