...At this point, why is the author even bothering spending time hyping up the villains and laying out their plans if its all just go to be beaten and destroyed like that. Its fucking annoying.
Just slaughter everyone and revel in it. no need to waste everyone time with stupidly one sided "fights".
Because it wouldn't be half as delicious otherwise, even if the premise and setup is cliche and even hamfisted.
And on a more foundational note then there wouldn't even be a story. One wonders why you're reading this if not for this kind of thing...I personally found seeing Elly have her moment all worth it. She's been hyped up for quite a bit.
Putting that aside....Light really does care huh? Quite a valuable items to toss away. But something not said is that he clearly does suspect involvement by higher powers, possibly Masters. Using the item is a precaution. It's not the first big move his faction has made, that ship sailed with the annexation of the Elf kingdom. But it's the first time they're doing so against these mysterious players.