as an example, planar pendant proc, definitely as a mage/rogue, we don't want to get hit too much

so, my suggestion is make the proc's chance to be variable, based on damage taken and health:

e.g.: based on damage taken compared to health, like the proc has a minimum chance (around 10-15%) and every damage that deals in multiplication of 10% of health, the chance increased by 5%. so a mage with 3000 hp when hit by 1501 damage (more than 50% of mage's health) has a chance of triggering the proc by 15% + 5x5%, which equals to 40%.

the increment value and scenario is just an example, so definitely need to be tested a lot, until we can reach a reasonable value, but anyway, please consider this to any next proc you're going to release (or already released one)

thank you