[Christopher R. Rice]

Originally Posted by qchap

Here I have a question about modifying the Draining disadvantage. I couldn't find anywhere a modifier, which could make the disadvantage drain FP, not HP. Or, especially, I'd like it to drain ER, but it doesn't really matters, I think.

First, to make Draining work on FP you could borrow the limitation from Weakness for Fatigue Only. That's -50%. In GURPS Proper substituting FP for an ER is generally a -0% trait. So "ER Only" would be worth -50% on Draining

Originally Posted by qchap

Also, I'd like to have some way to change the amount of draining per day. What if I want it to drain not 2 HP/FP/ER, but only one, or maybe 3.

I'd half the base cost for 1 HP/FP/ER and increase it by 50% for 3 points instead of 2.

Originally Posted by qchap

And finaly, not really so related question, but is there a way to make a character suffer from having low or none ER? Like make a character suffer from some temporary disadvantage, if it's ER is lower then some number (or lower then half of Will score, for example). And make the character to fall unconscious if it's ER is empty.

Yes. But it's complicated. You'd need to use a mitigator on the disadvantage itself. Then figure out when that disadvantage comes into effect. If you gain the disadvantage at 1/2 ER gone then it's worth -40% as a limitation, if it's at 0 ER gone then it's worth -60%.