Não somente Drenagem de habilidades faz
Isso é o que James Jacobs (Diretor Criativo da Paizo) disse sobre isso (post original):
I am confused on the different types of Ability Damage, Drain, and Penalty. Plus some spells like Ray of Enfeeblement and Touch of Idiocy seem to even have special rules. How do these effects really work?
Ability damage only results in a penalty to actions associated with that ability score; it does NOT make you lose access to feats or spells that require ability score minimums, since your actual ability score does not lower. Only ability DRAIN can make you lose access to spells you can cast or feats that have prerequisites.
But it's not that simple. Some effects that cause ability damage or ability penalties DO have additional effects. Touch of idiocy is one such spell, since it says in the spell's description that it affects the target's ability to cast some or all of its spells if the penalty imparted to the ability score drops low enough. This is an exception to the general rule for ability scores and applies only to touch of idiocy (the point of the spell, really, is to be a lesser version of feeblemind that screws over spellcasters, after all).
Ray of enfeeblement, on the other hand, does NOT have this type of language. It merely works as a normal penalty to an ability score.
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A 12th-level wizard with a 16 Intelligence takes a 3 point Intelligence penalty from Touch of Idiocy. What is the highest level spell he can cast, sixth or third?
Third.
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A 12th-level wizard with a 16 Intelligence takes 3 points of Intelligence damage. What is the highest level spell he can cast, sixth or third?
Sixth.
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A 12th-level wizard with a 16 Intelligence takes 3 points of Intelligence drain. What is the highest level spell he can cast, sixth or third?
Third.
A fighter with 13 strength and the Power Attack feat takes a 3 point Strength penalty from Ray of Enfeeblement. Can he Power Attack?
Yes.
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A fighter with 13 strength and the Power Attack feat takes 3 points of Strength Damage. Can he Power Attack?
Yes.
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A fighter with 13 strength and the Power Attack feat takes 3 points of Strength Drain. Can he Power Attack?
No.
Este esclarecimento é consistente com as regras sobre Drenagem de habilidades, Que diz:
Ability drain actually reduces the relevant ability score. Modify all skills and statistics related to that ability. This might cause you to lose skill points, hit points, and other bonuses. Ability drain can be healed through the use of spells such as restoration.