In which Batman is going to be pissed off

So recently I was thinking (and admittedly I don't really know how my brain connected these two ideas) but Batman has one rule. No killing. He's so zealous about it that he'll even enforce it on other heroes associated with him like Damien Wayne or Red Hood [to varying degrees of success]. In a potential fanfiction though, If Batman had to deal with the Holy Grail War deciding to happen in Gotham he would not be happy, and it makes me wonder how he'd end up stopping people from being killed given the way it works.
For those unaware, in the Nasuverse, the Holy Grail War is a system where seven[ish] masters and seven[ish] servants compete for the right to use a magical artifact aptly named the 'Holy Grail' in order to gain a free wish that can do... well, just about anything [usually]. Here's the rub, and the part that would piss Batman off. The Holy Grail requires the souls of six dead servants in order to manifest. Literally the only path to an end for the Holy Grail War is 'last man standing on a pile of corpses'. Of course, Batman has dealt with crazier shit, and always finds a way through it without breaking his own one rule or allowing it to be broken when he's involved, so... again. Just made me wonder. Could be a pretty neat idea for a fanfiction. Especially if I guest starred a few characters like Constantine and Zatanna. I don't know. What do you all think?