Dr Mundo may be headed for a rework in the future but one player has managed to earn a gargantuan amount of mastery with the champion while his good old kit is still around.
There are players who are one-trick ponies (OTP), there are those who love a League of Legends champion and then there are those who are completely dedicated to one.
Sheriff Bufford from League of Legends' North American server is probably a mix of the latter two since the one-trick ponies don't have this many points on their favourite. For example, at the time of writing, the streamer known as Yasuo OTP - Mohammad "Moe" Abdalrhman only had 2,421,396 mastery on his in-game namesake even though he is streaming LoL for a living.
Meanwhile, the good ol' Sheriff has amassed more than four times that amount on the pink doctor who tends to forget his name. Sheriff Bufford appears to have two fallback options when Mundo is not available - Singed and Olaf.
None of the champions have highly impressive stats according to the player's op.gg , not even the 10 million mastery Mundo, but that didn't dissuade Bufford from reaching for the dream and hitting the huge milestone.
So, what rank might such a behemoth of mastery hunting be? Well, it appears he was in low Gold elo on December 7, 2020, but it's hard to say if this truly reflects the player's skill.
The important part here is, after all, that Sheriff Bufford persisted with his favourite champion until reaching more mastery than most of us probably ever will, on all champions combined.