Dark Tianji slightly relaxed, because no matter what, this was at most half an Ultimate Kill Technique, and not yet to the point of being beyond salvation. In fact, although Six Harmony Creation has the foundation of reaching an Ultimate Kill Technique, it's still too difficult to truly attain that level. The Thousand Thunder Judgement Hell was able to reach the level of an Ultimate Kill Technique because it experienced thousands of years of thunder condensation, even capable of giving birth to weapons of divine artifact caliber like the Thunder Prison God Axe, hence attaining the power of an Ultimate Kill Technique. Since the Six Harmony Creation has not been in existence for long and lacks sufficient Wood Element support, its increase in size will slow down, and truly breaking through a hundred meters in diameter is almost impossible unless a substantial amount of Wood Element is infused into it to possibly realize that feat.
