This is my preferred slaying build for Neo Splash:
This is my support build:
You can go somewhere in between if you feel comfortable with it.
The Damage thresholds are 2 subs, 2 mains worth, and 2 mains 1 sub's worth.
As far as tournament placement goes, I'm probably the most successful Neo Splash, so if you have any questions let me know. I don't use it as much anymore because I'm usually using Zimi instead, but the gun is actually really good.