Samoa Joe's finisher in wrestling was always the Muscle Buster. It's one of the most devastating-looking moves out there but for Joe's entire main roster run in WWE, it wasn't used.
This was because of an incident in June 2015 when Samoa Joe, still an NXT superstar, wrestled Tyson Kidd in a dark match. He finished the bout with the Muscle Buster, but it ultimately resulted in Kidd's career ending.
The last Hart Dungeon graduate, Tyson Kidd, suffered a severe neck injury and was forced to go in for immediate surgery. He miraculously recovered and revealed that only 5% of people survive the injury. In 2018, the Wrestling Observer Newsletter commented that WWE banned the Muscle Buster more out of respect for Kidd whose real name is TJ Wilson:
"Samoa Joe has safely done the move for two decades, although WWE has banned it, more out of respect for Wilson than the idea it’s dangerous."
However, in 2018, Samoa Joe said that the Muscle Buster wasn't outright banned by WWE:
"The Muscle Buster is something I use at my pleasure when I choose to. Trust me, when the opportunity arises and the conditions are right, you never know what I'll pull out. Maybe I'm not ready to pull it out of my arsenal yet."
Some have compared the move to Kenta Kobashi's famous Burning Hammer - largely considered among the most dangerous moves in wrestling. However, Japanese legend Kenta Kobashi (once an opponent of Samoa Joe) rarely pulled off the move.
Samoa Joe still used the Muscle Buster after the injury happened during his feuds with top stars like Finn Balor and Shinsuke Nakamura in NXT. However, on the WWE main roster, where he had a 3-year run, the Coquina Clutch was his finishing move.
The Coquina Clutch is undoubtedly effective, but it didn't hold the same power as the Muscle Buster.
Samoa Joe finally used the Muscle Buster in 2021
Samoa Joe had his first match in one-and-a-half years at NXT Takeover 36. In his first match back, he challenged Karrion Kross for the NXT Championship.
The match led to Samoa Joe pulling out the Muscle Buster for the first time in nearly 5 years to become the first-ever 3-time NXT Champion. It was history for the Samoan Submission Machine, and an indication that he has a little more leeway in NXT than on the main roster.