Hi, i need some explanation on how applying a debuff is done... 

My Yufine have 100% chance to mute on her S2 with her unique item, she also have 171% effectiveness (base 121% + 50% from cursed compass).

Most of time in PVP opponents resist to be muted, on the last 10 PVP matches, only 2 times i muted all opponents, 6 times i mute 3 of them and 2 times i mute only 2...

So what we really know on how it's calculated ? Is there a soft cap for effectiveness? A base resistance that cannot be reduce?