Bai Di was a supreme-grade mutation of the Black Tortoise race's bloodline: A Void Lightning Tortoise.
If a normal Black Tortoise's biggest specialty was its powerful defense and extreme longevity, then Bai Di was even more freakish.
Not only was his defense very strong and his life very long, but he was able to rapidly create lightning and had an innate affinity for void control. He possessed the legendary "Void Escape" technique.
When using the Void Escape technique, Bai Di's physical body and the void would become one. A void protection barrier would form over his body and merge with his own shell armor, which could fend off at least 90% of all attacks.
His defense was even more powerful than a pure-blooded Black Tortoise!
It could be said that Bai Di's attacks were not that powerful amongst his peers, but his ability to protect himself was second to none.