Rufus accidently used on a hard disk, now a whole raid box has been wiped

Akeo won't be able to help here, unfortunately. Testdisk and Photorec may provide recovery.

After formatting the wrong partition I only perform dangerous operations on a separate laptop personnally.

Rufus author here. First of all, the proper channel to report issues is the official issue tracker.

I'm afraid however that there is not much I can do for you.

I literally went out of my way to ensure that large disks are not listed by default in Rufus and that, if you do want to have those listed, you must forcibly enable the hidden "List USB Hard Drives" option, which I will assume you had to enable to get that RAID drive listed. However, since Microsoft is really not helping with providing means to figure if a drive is a harmless external flash drive or your super important work backup drive, there's really only so much I can do, and the onus remains on you to ensure that you are really formatting the drive you actually want to format.

So, as per this FAQ entry there's not much I can do for you here. Rufus will have overwritten the partition table altogether, so, unless you happen to have had a backup of that, you're pretty much screwed. One thing that may potentially help, if your drive was using GPT and was converted to MBR, is to look at the last 33 sectors of the drive as it may still contain a backup copy of the old GPT you were using, but, as other people advise, you will either have to restore from backups or consult a data recovery specialist.

Now, if it happens that Rufus was somehow listing your RAID drive by default (which, again, I can't be held responsible for, as I provide no guarantee that the HDD vs UFD detection algorithm used by Rufus, which I had to create from scratch, is 100% accurate, especially if your RAID controller reports your drive with the REMOVABLE attribute, or if you created a VHD on top of it), I am interested in your Rufus log which you can access with Ctrl-L (you may also want to press pressing Alt-. to turn on enumeration debugging) so that I can improve Rufus to avoid others running into the same problem.

But I'm afraid I don't have a solution to "fix" the formatting of your RAID drive, and you will have to either use your backups or consult a specialist.