Psionic abilities, like skills and spells, are trained abilities. The definition process is accordingly similar.

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>>  What Stat is this Psiab based on?
>> [Enter stat, or .q to quit]
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Like skills and spells, psiabs require a base stat. The norm is for psiabs to be based on Intelligence.

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>>  Does this Psiab have prerequisites? (y/n)
>>  What is the category of this prerequisite?
>> [Enter stat, skill, spell, psiab, advantage, disadvantage, or .q to quit]
>>  Which Advantage is a prerequisite?
>> [Enter Advantage, or .q to quit]
>>  What level of this prequisite is required?
>> [Enter number, or .q to quit]
>>  Prerequisite added.
>>  Do you want to specify another prerequisite? (y/n)
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Again, you can specify whatever prerequisites you feel are appropriate to the world you have developed. All the standard psionic abilities require the Psionic Aptitude advantage as a prerequisite, but this is not required for newly defined psionic abilities. (Note that advantages and disadvantages must be selected during chargen: with an advantage such as Psionic Aptitude specified as a prerequisite for all psiabs, player's cannot simply decide to `become psionic' when they accumulate enough points in play. The decision to play a psionic character will need to be made at the outset, during chargen.)

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>>  Is there a monetary cost to learning this Psiab? (y/n)
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Although none of the standard psiabs do so, you may set up psionic abilities in your world in such a way that they require training. Giving psiabs a monetary cost to learn would be a way to simulate this.

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>>  What is the Fatigue Cost of casting this Psiab?
>> [Enter cost, or .q to quit]
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As with spells, the fatigue cost of psionic abilities is the primary means of ensuring balance. Psionic abilities (and spells, for that matter) which affect stats should have a fatigue cost greater than the modification to the stat (a psiab that temporarily adds 1d8 to Intelligence, for example, should have a fatigue cost of at least 8). Extremely powerful psiabs should be expensive enough in terms of fatigue that they require characters to buy Strength and Constitution up to moderately high levels (10 or 11, say) before the psiabs could be used at all (that is, assign fatigue costs of 40 or higher).

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>>  Does the target of this Psiab get a roll to defend? (y/n)
>>  What is the category of the Ability the roll is based on?
>> [Enter stat, skill, spell, psiab, or .q to quit]
>>  Which skill is the roll based on?
>> [Enter skill, or .q to quit]"
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All hostile psiabs, and many helpful ones, should be assigned a defence roll. The standard psiabs allow either the Mental Discipline or the Mental Resistance skill as a defense. Using either one of these or the Presence stat is recommended.