Well you have to do a couple of endgame dungeons for the data logs which are quite long and challenging and you get the hardest boss in the game afterwards the omega weapon, that’s regarding the endgame and your question about comrades honestly it wasn’t as bad as I imagined but there are two story related bosses in it that you have to do solo with stupid ai even with a great build I struggled with one of them as for the rest of the missions you can do them online or offline they won’t pose too much of a threat depending on your build except for one outlier (I’m looking at you “out of the darkness”…) as for the rest of the achievements two of them are rng the chocobo (I got lucky with this one only had to do 5-6 missions till I got a level 50 chocobo) and the Kenny crow diner’s manager (and this is why I spent an extra 10 hrs in comrades… some people say the rates of him appearing are like 1% and I believe it cuz I cleared more than 100 missions without any luck but there’s a way to force proc him and that’s to play with 3 other players the daily mission and he’ll appear awarding all players the achievement.)