Chapters: 450-459 (General Zombie Night - Death Isn't An Apology).
Title: "Demon from the Frozen Land" or "Death Isn't An Apology."
Cover: Brook and Ryuma clashing swords in the foreground, behind them have Moria, in one hand holding Luffy's unconscious body and in the other his shadow, potentially with some silhouette of Oz in the background. I just think this'd look cool, don't really expect it to look like this, haha.
Might be cool to have Laboon somewhere, but that;d be waaay too spoilerific. But, given the volume cover of vol 45, it's not wholly out of the question.