Check the mod priority guide:
https://docs.google.com/spreadsheets/d/1ty239kyJbBs1sLhTo1JvSWuN0mIJsK1nwVdI6OLLtXo/view?rm=minimalRO635 MOD is something quite interesting. Have you ever wanted to see a doll that can theoretically stare an enemy right in the face and give it the middle finger as its attacks bounce off her with not a scratch dealt? That… typically won’t happen, but RO635 could do it if RNG goes her way.
Her Skill 2,
Righteous Judgement, allows her to potentially dodge a lot of incoming attacks. When she is hit by an attack that deals less than one link’s worth of HP (before linksplash), she has a base 20% to roll a second evasion check that also works on surehit attacks. The chance to roll the second evasion check increases with the amount of (certain types of) debuffs on an enemy, with each layer granting RO an additional 10% chance. When Skill 1 is active, the base chance to roll the second check goes up to 40%.
The main downside to this skill is how it can be potentially ignored. However, there are very few enemies which would actually deal enough damage in a single instance to ignore it, and typically you wouldn’t be having RO fight these enemies in the first place anyway. Besides that, it is still pure RNG how much this skill will protect her. Sometimes it will work in her favour, sometimes it will not. When we’ve now got other upgrades that offer consistent protection for the tanks, RO has fallen behind.
Besides this, RO gets your typical suite of upgrades. Statwise, she focuses primarily on HP and Evasion upgrades to bring her default tankiness up even further. Her Skill 1 gets a second debuff and her tiles also get slightly stronger.
With 2 layers of evasion checks and really good stats, with proper setup, RO635 MOD does serve as an effective tank. However, there are other SMGs that tank better with less effort, most notably Suomi MOD.
MOD2 is her best stopping point, you’re here for the skill and everything else is bonus. MOD3 is a good upgrade, but for 5 FCCs you really want more than just 1 point of HP and an improved T4 Exo.
…Actually, MOD3 does have her incredible art. She looks so cool and mature and comforting… Is this definitely RO MOD? Seems more like RO MOM to me.