HallOfGiants remains my fave map to test most everything on, and the Cyberus (a largely un-killable monster) is something I'm still toying with:
(http://ic.pics.livejournal.com/evilgrins/3189901/4115153/4115153_original.png)
So this little experiment is for sheer fun. Cyberus is in a spot where he's largely out of the way unless players goto him first. It's a Deathmatch map so fighting him isn't necessary... but you might wanna choose to avoid him.
Originally changed his projectiles to NW2 ultima-protos blasts, then paired that down to projectiles from the UKBadBoy, and finally settled for energy attacks from the Udoom weaponpack: plasma blasts & BFG:
(http://ic.pics.livejournal.com/evilgrins/3189901/4115245/4115245_original.png)
Thing about the BFG is that it hurts the monster firing it as much as everyone else, so the fact Cyberus can't die works out well here. It's a line-of-sight blast, so if you see that slow moving green energy ball you should duck for cover.
Enjoy ยท http://www.mediafire.com/file/8t65kt61z6vtxqc/HallofGiantsV2Cyberus.zip