I don't use them. The benefit is that if you are incapacitated they still function. The detriment is it gives more reasons to purge you and there's always the chance that it just fails. I don't like actually using defenses. I like that defenses make my opponent think twice about lobbing that boulder at me.
I think the real issue with mage defenses is that you have to use a quick action to put each one on, and each one only stops one attack. So they're good if opponent has only a few creatures, but if they're swarming then mage defenses are not as useful. I might consider using force orb to deal with acid ball or boulder after they surging wave you, but that's kind of a niche use for force orb.
Also, now that Forcemaster has symbiotic orb, she doesn't need to use other defenses against melee attacks most of the time, not unless she really needs to save mana or dissipate tokens.
That being said, there are some other corporeal creatures that would really benefit from a defense unaffected by conditions like daze stun or incapacitated. For instance, anything with a weakness to lightning. Like Brogan Bloodstone.
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