Diligence + ith boss debuffs

Version 10.3, Win 7.

Fighting an Ith portal boss that gives out random debuffs on the start of battle. I have Diligence equipped, but the silence debuff it gives out still silences my creatures, even though they have taken no damage. Also, it can give out multiple copies of debuffs - one of my creatures has 3x burn debuffs, another has 2x silence debuffs.

Edit: Scorn and silence also stack with these 5 debuffs, as one creature has both and is unable to cast or attack.