tenacity vs potency

The difference between potency and tenacity gives a %chance of applying the debuff. The higher the difference, the greater the chance. But there is always a minimum 5% chance to apply a debuff and a minimum 5% chance to resist it.

Tenacity - potency = chance to resist (min 15%)

This is a single check that happens after the chance for the effect to happen (according to the skill description )

I'm not sure I understand your question.

First you have to know if the ability has % chance to apply. For example - Resistance Trooper has 65% chance to apply Expose on his basic attack. However once he passes the 65% chance, he also needs to go through potency/tenacity check.

So in other words, if you have a hero that has 100% chance to apply debuff, this debuff still goes through Tenacity/Potency check UNLESS it is specifically stated that it Cannot be resisted. An example of such debuff is Thrawn hitting someone with ability block, it doesn't matter if they have 31894318948913489189431894% tenacity, he will still stun them.

Crazylazyguy, what I was thinking was that it first does a success check (like your resistance trooper example). Then upon success of that, does a potency check for the attacker to see if he applies the debuff, then upon success of that, does a tenacity check to see if it is resisted. And the tenacity check trumps all. I was pretty sure it worked more like kyno said, but I'm having almost no luck with my Palpatine lead stunning people. Before going into the battle he has 103% potency. With his leadership ability, should be 133%. And I know it only has 70% to hit, but I've been looking at my arena opponents tenacity before I go in, and with no tenacity mods on anyone, I'm LUCKY if I get 2/5 stunned. And if I'm against a Palpatine (not even as leader), I routinely get 4-5 of mine stunned. Very frustrating. But it is what it is I guess. Thanks for the answers