[quote=Masaki Haruna]
Is Devil Slaying Magic allowed?
[/quote]

I do think the magic has potential to be awesome. So i don't think it should be much of a problem. However, we don't know too much about it. Other than the assumption that it works pretty much just like Dragon or God Slayer magic, but with the devil aspects. Still it's likely that it'd be on the same level as any other form of magic, just like God Slayer or Dragon Slayer is. So it's not like it'd be overpowered. 

Oh, but you cannot make reference to the story arc where it is introduced as soren is only around the S-class trial arc. Besides if we work the story properly we won't need to use spoilers much if at all.