Ability Damage (3.5e Variant Rule)
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 Ability Damage
Rather than dealing nonlethal damage, strain deals ability damage, temporarily reducing one of the user’s ability scores. All psychic skills may reduce the same score or they may each reduce different scores. Perhaps each psychic talent is associated with a particular ability score that it weakens (using Psychokinesis damages Wisdom, for example, while using Telepathy damages Strength). Psychics may also have the option of choosing the ability score affected by the strain of their skills, either when the skill is learned or whenever it is used.
The ability score damaged by strain influences how strain affects the character. If Strength is drained, then psychic skills produce fatigue and weakness. Damaging Dexterity means psychic skills produce disorientation, clumsiness, and slowed responses. Constitution reflects psychic strain directly affecting the user’s life energy, meaning that overuse can result in death if the character is reduced to 0 Constitution. Intelligence, Wisdom, and Charisma reflect a reduction in the character’s mental capacity due to disorientation, fatigue, or an excess of psychic energies in the brain.
If strain deals ability damage, then psychic abilities become far more dangerous and difficult to use, and the capacity for using them doesn’t increase with character level. A character’s overall power and ability (skill rank) may increase, but since ability scores increase slowly at best, a high-level psychic cannot use or sustain skills much longer than a low-level one. A number of psychic actions (those with a strain of 18 or more) also become effectively impossible, since few psychics can suffer so much ability damage. Since ability damage recovers slowly, psychics also use their skills sparingly, only when absolutely needed.
This option is most effective in campaigns where psychic skills are the only special abilities available to player characters (or other special abilities are similarly limited). Perhaps damage to Intelligence or Wisdom can also reflect psychic skill use slowly eating away at the user’s sanity, with overuse leading to madness.