
If I remember right (and I gave it a quick skim), his fight with Paimon went a little sideways so he unfortunately had to use Limit Break to kill Paimon. If I reread right (because he never used this skill again in Season 2 so I forgot all about it), Limit Break kills don’t give life back to him in exchange for upping his attack significantly. Pair that with his sword which eats at his life and I think he overused that slowing time skill of his, he ended up killing Paimon at a loss.
He’s hoping that this time with the demon queen, he’ll be able to more efficiently kill her with all the allies and extra strength he built.
So he’ll kill the demon queen to earn more days? But why when he killed Paimon, he lost his days instead? Did I miss anything??