If you check NativeMe' s channel, he has an ML Surin cleave - ish built.I have her 6* but do not use her yet till she has good gear.In my opinion her use is very niche. I could see her in Guild Wars tanking some Dark heroes, paired with a cleanser/healer and another attacker. If you build her very fast, her s3 goes to waste when the opponent has immunity, so u need a whole team setup to use her,unless you do a second turn team that has a lot of survivability.Personally, I prefer my heroes to be able to be more standalone, rather than have a specific combo position, so I would build her with Lifesteal /Immunity with a lot of hp, atk, crit chance and damage with an average speed.For artifact go for Moonlight Dreamblade or Sheppards of Chaos for more sustain.I would suggest also to save your Mola Goras for more broken heroes. 4* heroes need really good gear to shine like a 5*. That's why after 46 6* heroes, I started raising 3* heroes since their skills are easily upgraded and are useful.

^ in the same boat with Spellstorm. She isn't OP in anyway, and can serve as a good pseudo bruiser at best. Save molas for heroes you have the gear for. 

I agree lifesteal/immunity with some evasion.