Hey guys! So, this may be the wrong section to ask this, so direct me further if need be.

I decided to pick up DAI dlc packs lately after not playing for a LONG time. During my initial play throughs when the game was new, I played a rift mage, a dual dagger assassin, and a 2h reaver qunari, so I decided to go a new route this time and run a dps necromancer.

From what I remember, certain allies back then were kind of risky to bring. Black wall seemed to be kind of a must have with his ranking abilities, and viv tended to be the same for her reviving and spirit blade. This time, I wanted to bring along some people I haven't played with before, but I'm not sure how to use them. So I thought maybe I could ask you lovely people for some opinions.

I wanted to know first if Cass was usable as a party member, and if so, what is a good build for her? Does the AI like to play nice, or is she like Bull and get herself killed every two minutes?

As for My rogue, who tends to work better as a teammate? Sera or Varric?

Finally, last question. If I am running barrier myself, is it essential to bring a support mage or could it be possible to substitute for another dps?

Thank you to anyone willing to help direct me. And thank it all for your time. You all have a wonderful day!