Should I raise mashu?

YES, Nero can't give you the same support that Mash. I have both and I prefere to use Mash as front line support and Nero as subparty member (4th slot, she can make both rols, support and DPS depending the situation).

against lancers you could use Nero as DPS and Mash as support

Mash shouldn't be comperad with Vlad because he is a tank DPS and Mash is a support.

Her skills are some of the cheaper on the game and are very usefull.

An finally but not less important her cost is 0, on events it's very usefull.

Duh level her up right now

Nero Bride isn't a support. She's halfway between support and dps.

Mash is a full Tank. She comes in useful, especially for soaking a single target NP if you use the Mystic Code that lets you swap people from your backline in mid-fight without someone dying.

Yes. At the exclusion of all other servants.

There's nothing I can tell you that isn't already on her gamepress page. She's a fantastic servant, if for nothing but her 0 party cost.

OFF COURSE.

Especially if you are lacking of SSR. Mashu is the best.

mash is genuinely one of the best supports you can get, she costs nothing, i have all her skills at 10, shes maxed and you bet she saved me multiple times during nerofes

Not to beat a dead horse, but Mash is genuinely one of best servants in the game. Her skills, 0 cost and tankyness allow her to fit in almost any team and only gets better as the game progresses. She was my first maxed Servant, and the only one I have gotten to 10 in all skills.

Post Camelot she is a beast. Get her to max lvl and skills asap. You wont regret it. She is a front line constant in nearly all my teams. She is hard to beat. Especially on an arts team and I have Jeanne and Tamamo.

Like mentioned above by people, she's totally one of the best of the best.
Zero cost and her kit is a total dedication to her job.
Like Hans and Waver, the differences is they're supp and she's a Tank.
I must say, like father like daughther Lancelot is a Broken Saber and the same goes to his daughter, Mashu the Broken free Tank.
My must - to - use unit on an unfavorable match/battle and also the peoples choice.

its pointless for me to keep on prising mash, anyone here alredy told you enought.
To me she is by far the only reson i was able to beat camelot whit only 1 ssr servant and 3 sr. Well thet 1 ssr is cu alter, so...
But... i would have not be able to win if not for her. She is foundamental for my team. even more for your jalter (who is easy to kill). and her post camelot NP is crazy strong.