Story: Gorilla Warfare (Priest #35)
Background: T'challa travels to the Crystal Forrest with Agent Gyrich, in order to get QDJ back from M'baku. While there, among other things, T'challa is challenged to the Tribal Challenge by M'baku. Due to QDJ commanding M'baku not to destroy T'challa, T'challa first states that Gyrich will fight for him by proxy. After finishing up other matters, T'challa rejoins the challenge himself.
[Scan Tip: Click to enlarge the images and they are easier to read. You can scroll through them all that was as well. --- Shadow]
What M'baku revealed was another Black Panther... and... that is a long story involving brass frogs, time travel, and other shenanigans lol