I helped out a corpmate friday night when he requested some support for gallente epic arc missions. I took a tank focus Rattlesnake and a Scimitar to back him up. EHQ indicated I would have be able to tank something like 3000dps with the fit. The first mission went fine. I warped in, took agro, shield went down a little, and then scimi landed and no problems. The next mission though got interesting. I had to refit for omni tank and I didn't consider neuting so I put on active hardeners instead of passive amplifiers for resists. The fight was going fine to begin with but my rattlers cap was slowly going away. Once the cap died so to did my resists and my shield was getting gouged. Fortunately we killed a BS and at that point the scimi was able to keep me up alone. I sat on half shield the majority of that mission but we finished in the end.
Lessons I learned for future epic arc missions: use passive resists when going up against neut ships, bring multiple resist modules along, and epic arcs look fun. I think I'm gonna look up some Caldari arcs and perhaps give them a go.