This isn’t related to the mod it self, I just can’t figure out the command /witherstormmod cluster

Taken from the official discord:

"it's pretty much like the /fill command. you specify one corner than another, which tells it "all the blocks in between these two corners will be put into a cluster." the next argument is the time it's allowed to exist, i usually use 100. the next argument is NBT. since clusters spawn with gravity by default (causing them to get placed back immediately) put {NoGravity:1b} to disable it. there's no way to make them get absorbed by a wither storm atm."

If you need further assistance with stuff I recommend joining the discord instead of asking for help here :)

Thanks!