There actually are low RNG and even zero RNG builds - at the cost of some dmg potential of course. I couldn't figure out a way to run the meta light build for this dummy without having to RNG DATA on one or more himes (and doing it with earrings instead of tiaras.) I ended up going with a build that guarantees the planned burst as long as the right himes are killed off, so it's basically a 1/6 chance of working. Finished all 6 elements with around 40 tries-ish.
I also experimented with a couple of zero RNG builds - just FB on T1 and call it a day
This was enough motivation for me to NOT try for high RNG builds
Also need time to farm Ophiel before the rush is over, she looks like a total pain to do later.