Li Shenron
Legend
Awakened said:Has anyone figured out a way to make called shots more circumstantial, as in, used at the same frequency as Trip/Grapple/Disable/Sunder?
You've just answered your own question

Make call shots not convenient unless the PC has a feat that reduces the penalty.
I think the DMG has a small table of effects on different body parts, which can be used for called shots.
Try to evaluate how much of an attack penalty balances the benefit of hitting each body part.
The target of this is to make sure that called shots are a valid option, but not better than attacking normally.
Once you have a list of targettable body parts, each with its own penalty, make this a combat option available to anyone.
Then, if you want to reduce the rate of called shots in a game, just increase all the penalties by -4 (hence making them straight underpowered), and introduce a feat Improved Called Shot that removes the -4.
A different way is to make called shots not_open to anyone. So instead of making it a generic attack action, make it a feat since the start.
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You can also design called shots completely different: for example you can consider tying called shots to critical hits. Have the effect of a called shot (i.e. leg->slowed, arm->penalty to attacks/skills, eye->blinded ecc) come into play replacing the extra damage bonus in a critical hit.
You could, if you want, require feats to be able to make a called shot. For example there could be a feat called "Blinding strike", that allows the character to forgoe all the extra damage in a successful critical hit in exchange for causing his critical to blind the target.
You can then balance different effects by using penalties to the confirmation roll (bigger penalties for using a feat whose effect has much more dire consequences on the target).
You can even use these penalties to balance weapons with different critical multipliers. For example a x3 weapon could give a +1 to the confirmation roll when using a called shot feat, a x4 gives +2 ecc. This way, a weapon with a better multiplier "wastes" more damage to get the same called shot effect, but gets at least a better chance.