The GM needs to design the type, number allowed, and drawbacks of Powers in her game. Some examples:
Types of Powers: a given campaign may allow magic, psi, superpowers, etc., or some combination of the above. The GM also needs to decide how finely a supernormal power is subdivided. Is ESP a generic Power, or is it split into separate Powers such as Precognition and Clairvoyance? Is magic subdivided into spells, or groups of spells (such as elemental magic) or simply the ability to break the laws of nature in any way that can be imagined? And so on.
Number of Powers allowed: the GM may set the number of Powers allowed per character. The number may range from one to 20 or even more. Multiple Powers per character are especially likely in a fantasy campaign where individual spells are separate Powers.
Drawbacks of Powers: in some campaigns, using a Power may bear a penalty or have some drawback. Typical drawbacks include mental or physical fatigue, lengthy time requirements, unreliable or uncontrollable results, and undesirable side effects (such as loud noises, bad smells, and the like). Some Powers will only work under certain conditions or with certain materials, or are limited to a certain number of uses per day or month.
Others may be risky to the character, affecting physical or mental health. The GM may allow drawbacks to count as faults: a number of them can offset the cost of a Power in the Objective Character Creation system.