With this update, things are really alot different then they used to be. Changes may affect classes alot in midle levels. It look more like ToO times, that was lvl75 cap. Back then Angmar map wasnt fun and games at all, on level.
There should be markers in quest log showing is it single player, small fellw 3man, fellow 6man, or raid 12 man quest.
Some fellow quest areas on map are in Lonelands, Red Swamp, North downs south east corner? Rewamp? North western part of Angmar, Northern Trollshaws? Rewamp?, Misty mountains South east corner, anything with giants. No such things in Eregion, only few signatures. Lothlorien, Mirkwood, that i know of, some fellow quests. Same in Dunland.
Limlight is fellow quests only. After that its pretty much all single player areas. Ofc warbands are not ment to be soloed, but many did so. That is until now. Still, some of em hit pretty hard and can oneshoot any player, any class. Especially so in HD. Not all of em, some are pretty weak.
About mitigations, in raids, tact mitigation is must habe again, many bosses deal unavoidable attacs, tactical aoe. On a map, mostly all damage is physical. Retraiting on a spot is good idea, to try out how it works. Max resist and physical mit for map, tactical for instsas it used to be.
12 k shards where spent bsak in days, to get 384 crit defence. Some of that too.
And keep in mind, evrything changed. Old assumptions dont work. And dont belive me or anybody here. Check and test. To give an idea how much is changed, try out Blind one in Skymful. Pretty interesting.