A headscratcher of a card. Most Guardians will be defeated by horror, not damage. This card will make you all but immune to damage effects.
Sadly, at the moment it seems too expensive (both resource and xp) to be worthwhile. I can see its merit in Mark Harrigan, who wants to preserve his health as much as possible for his triggers and to avoid his weakness... but even then.
Also it has a cute interaction with smoking pipe.
But still, really ask yourself is this better than a lightning gun? I would say 9/10 the answer is a solid no.
I hope there is some way of reducing this cards xp cost or they release a leveled down version at some point, because I have a feeling this won't see all that much play until then.