1. Debuffs are applied in two steps:
First: with 80% possibitlity, a concussion mine is placed.
Second: If the effect triggers the tenacity / potency is calculated. Tenacity of victim - Potency of attacker = Chance to resist debuff. This chance can never drop below 15%.
In general for maxed out ships, the tenacity is around 65% and the potency around 50%. This leaves still the minimum value of 15%.
The possibility to apply a concussion mine is then 80% of ability to happen times 85% of the tenacity/potency check, which results in a 68% chance to apply a concussion mine. So every third attack will not result in a concussion mine.
Source:
https://forums.galaxy-of-heroes.starwars.ea.com/discussion/135890/how-does-potency-and-tenacity-work
2. You have to be more specific here or better post a video.
It depends strongly on the turnorder, how long the taunt is active.
Eg:
Vader, B28 and Palp on your team. Vader falls below 100% health, B28 starts his passive taunt for 2 turns.
Next is Palp, who uses Royal Escort and B28 starts another taunt for 2 turns.
Both taunts are lasting to the same round. As they were started in the same turn for B28.
