Naruto: Obtain a Mutated Heretic Golem at the Beginning

Travel through time and become Bai, and obtain a mutated version of the Heretic Golem. The absorbed chakra can be transformed into any attribute of wind, thunder, fire, earth, water, yin, or yang. Once a certain attribute is accumulated to 100%, you can obtain weather-level ninja techniques. So Haku stayed in Konoha after becoming Danzo's root, and after several months of feeding, he built up his water attribute to 50%. Just waiting for the Chunin Exam Orochimaru to attack Konoha...