I Am the Walker of Eternal Silence, Slayer of Immortal Beings

The Eternal Silence Walkers have only one heir per generation, and their sole purpose is to kill immortals who seek eternal life. As my master lay dying, he shoved a knife into my hands, pointed at the glowing "bubbles" beyond the heavens, and told me to kill the Immortal Emperor who lived forever. The good news is, you could say I created this world. The bad news is, as the seventh heir, I'm about to drown in the Dark Tide I designed myself.