I had been meaning to ask if it was viable to bring Perfect Wife Mashu along for everything in the game so I'm super glad to hear she continues to beast.
Ok so I’ll give you The Timeline:
- Early Early Game: Absolutely viable because she overpowers pretty much everything.
- Early Game: While still viable, you probably have more Servants at this point that can outdo her, since her defensive abilities are not necessary this early in the game.
- Mid Game: This is where she suffers, because she’s very much a 3* when you most likely have a couple 4*s, some from quartz, some from events. Her stats will start to fall behind. You will still have her in your party because she has a cost of 0, letting you put all your strong Servants in the party without compromising party size. Most likely your disposable frontliner or your very last resort. Keep in mind she has a level cap you cannot increase, as he Ascensions all work via story line.
- Late Mid Game: This is where she starts picking up again, because she starts receiving her Ascensions and, surprise, she turns into a 4*, with the appropriate increase in stats. Her skills also get upgraded, especially her first skill, which becomes godly. Her NP also gets upgraded and ramps your damage to new heights. Putting Mashu together with Merlin or Zhuge Liang is basically the ultimate stall game.
- End Game (what is currently the end game, anyways): She will absolutely wreck shit, between keeping your people alive and not being bothered by complex enemy classes at all. With a taunt and invincibility, she can nullify enemy ST NPs, and if you combine her first skill with her NP, you can very much minimize damage from a partywide NP to survivable, if not negligible, amounts.
So yeah, be sure to cherish the kouhai.