Check the mod priority guide:
https://docs.google.com/spreadsheets/d/1ty239kyJbBs1sLhTo1JvSWuN0mIJsK1nwVdI6OLLtXo/view?rm=minimalUMP9 MOD gets an overall good upgrade to her abilities, though still suffers from most of the same issues that her base form does.
Statwise, her Evasion sees a nice improvement. Her tiles also see a boost in how much Rate of Fire they give, and her Stun Grenade now lasts for slightly longer. Her Skill 2,
Snowy Owl’s Roar, allows UMP9 to buff herself and the others in her column depending on what the Stun Grenade does.
If the Stun Grenade doesn’t stun her main target or said main target dies before the grenade hits, she and the others in her column get a small HP Shield and Evasion buff. If she does stun her main target however, she instead gives a significant 50% Damage buff. With the right timing, you can take advantage of this by moving UMP9 into the back column so she gives said Damage buff to your DPS dolls.
Sadly though, UMP9 is still a stun grenadier. Her ICD didn’t receive an upgrade, still too volatile in targeting, and the stun grenade still does not work on threatening enemies or bosses. Her usability remains niche overall.
UMP9 is definitely a good upgrade to a doll who’s sadly past her prime. She’s overall a low priority upgrade in terms of performance, but I know most of you will upgrade her anyway because of her story involvement and adorable smile. In that case,
MOD2 is the optimal stopping point. Her Special Equipment from MOD3 is a nice upgrade over a suppressor but not worth the cost.
Her SPEQ-Set buffs the radius of her Stun Grenade and inflicts stunned enemies with 50% Vulnerability. This is a pretty significant damage increase, but sadly still doesn’t work against unstunnable enemies.