Mash or Jack with Altera?

Jack after Natural body interlude since she becomes a crit servant with crit star gather skill, but for now Mash for defense and survivability.

whats your third member?

the way i see it jack is fairly self sufficient while having the added benefit of enormous star gen for the team whereas altera may be capable of some significant burst when her skills are up assuming you have that star gen going and can boost jacks np. its sort of a pair that supports each other. but altera is definitely the short end of it. given that she has 2 skills dedicated to increasing her own burst, but has an aoe np. its still capable of a buster brave chain tho so its not bad. it just means shes going to more or less be a waiting for her skills while jack does most of the work and then trying to burst when she can. tho as i said she can boost jacks single target np if the situation calls. the only thing missing from the pair is hard survival skills on altera which mash could actually take care of. jack and altera both have self heals which combo with mash;s defense ups and invincibility. that would be my preference because i want to always have hard survival available for key team members, but you could also forgoe mash for someone like hans who gives crit damage and much needed base attack up which you only have for one turn with altera otherwise.

i think i sort of talked in circles a bit, but i hope i made my point.

Both Jack and Mashu are decent as the 2nd or 3rd place in many team. They are indeed good in the utility consideration.

After Altera's 2nd skill upgrade (maybe this November), team with Jack is even more decent since you can utilize Jack for star generation, therefore Altera could deal very heavy critical damage, especially if you have Andersen, Nightingale, Waver or Merlin in the future as the third teammate. Before that, so far, you probably need a star adsorption CE for Altera (Teacher and I, Seal Designation Enforcer, etc).

On the other hand, if you paired with Mashu, means you want a team worked more tanky and Altera worked as DPS, like a normal Berserkers team except Raikou's critical DPS. In this case, Altera could have CE to increase her attack or Buster card performance, or NP charged CE to release her NP soon.

A specific example is you have Altera + Mashu + Leonidas. Amazing strong if you can spam Leonidas's NP, then Altera's attacking could be beneficial by Leonidas' third skill and NP's star generation, and you don't need to consider any defense issue except enemy unleash a AOE NP.

Still, in my opinion, this could be significantly depending on what your team want to be, like what CE you want to apply and what your third servant choose, even mystic code worked different (Anniversary Blonde vs Combat Uniform vs Chaldea normal) in team. I cannot guarantee Jack or Mashu which one is good to pair with Altera as a team at this moment.

Like I may say that a team of Altera + Andersen with 2030 and borrow friend's Waver/Nightingale (or Merlin in the future) with 2030, using Anniversary Blonde as mystic code, you can finish a battle extremely soon and easy, which could be better than any teams I exampled (at least for NA so far). However, 2030 is just like SS(+S)R CE that everyone are greedy for.

If you say want to have one of Andersen, Waver, Nightingale and Merlin as the third place, but they also have different compatibility to either Altera+Jack or Altera+Mashu......................