Not sure what you're getting at here.

Do you mean an all or nothing 1 hit ghost?

Or do you mean an uber ghost?

Or do you mean something like in the forge where you gamble on what lvl of equipment you get if you haven't got all the same level materials so you attack a ghost but you don't know it's level?

I didn't respond to this when I first saw the post.

I took it to be yet another example of laziness and greed.

Instead of doing sustained attack,the player would just attack probably any ghost,without needing to look for a specific one. hit it with a certain amount of energy and gamble on what dropped,as you surmised,it would be a bit like the gamble taken when forging materials and hoping to get legendary when there was epic or something else in the mix.

What would probably happen is they would do this with lots of ghosts,hoping to get good quality items and leave them after that,not having to worry it being target by another player in the meantime, and thus robbing other players of taking them all the way to zero using sustained.

I think I see what you mean. Each current ghost type would have a 7th Unkillable level. You add your Shaman power to the max (or whatever you want to risk) and then have one hit which might do 785% (or some other big number) damage and you get a whole pile of stuff but the ghost doesn't die.

Can't see that happening. Too easy to get massive points at end of competitions.

But Uber ghosts wouldn't surprise me and they would be a bigger gamble because you would get runes for several different ghost types, some that you may not want.

UBER ghost would be a nightmare for specific drops.  ;-(