Since update 20, my character is regularly being affected by nerve venom, especially in raid settings. It's more dangerous then the neg levelling which would occur post u19 and seems to have gone now with u20. That was annoying, but at least deathward would prevent it. Since poison immunity was nerfed back with MOTU we have no such protection against nerve venom.
In a raid setting, when you have a number of casters and/or artificers with high attack rates striking a single target where melees are clustered, this is very dangerous both because it can make you helpless and it occurs quite frequently. In the elite ToD my group completed, I was frozen around half a dozen times during the final battle, and I could see it affecting other people too.
As far as I can tell, each time there is an update, someone is fiddling around with the proc effects table for double rainbow. If that seems like a good use of someone's time, that's great, although there are other things I would argue need more attention. But the end result seems to be that either someone is deliberately introducing fun and random effects which harm players, or the flags which determine whether or not players are affected by those effects are being inadvertently messed up.
Please stop making double rainbow effects harm players. It's just a pain in the backside, and is taking the whole 'random is cool' design principle way too far.