Skirmish on Byss
In the year 10 ABY of the Legends timeline, a brief conflict transpired between Imperial Military Executor Sedriss QL and a pair of disloyal Imperial Force Adepts.
Background
Following the most recent demise of Emperor Palpatine during the Battle of Pinnacle Base, Nefta and Sa-Di, the two Force adepts, plotted to seize control. They disseminated false information, suggesting Palpatine wouldn't return in a new clone body, and moved to eliminate any potential threats. Imperial Executor Sedriss QL was a key target, so Sa-Di publicly demanded Sedriss's execution, asserting that his performance in the Battle of Balmorra had eroded confidence in him. Sedriss quickly traveled to Byss to address these accusations.
Bursting into the Emperor's cloning facility, Sedriss discovered Nefta and Sa-Di murdering Palpatine's few remaining clones. When Sedriss questioned their actions with anger, Nefta explained that he and Sa-Di feared the Empire's collapse due to Palpatine's absence, believing he might be stuck in the Netherworld of the Force for thousands of years. They felt the Empire required a strong leader and sought to take that position themselves, so they acted.
The Confrontation
Sedriss agreed that the Empire needed a powerful leader, but he didn't think Nefta or Sa-Di were fit for the role. He ignited his lightsaber and launched an attack.
Only Nefta could effectively fight Sedriss, as Sa-Di was armed with a battle axe instead of a lightsaber. Nefta managed to resist Sedriss's initial onslaught, but was quickly overpowered. His attempts to use the Force against Sedriss were ineffective, only earning the Executor's mockery of his "magic". Sedriss bisected Nefta just below the chest.
After Nefta's swift defeat, Sedriss approached the cowering Sa-Di. Sa-Di tried to convince Sedriss that he hadn't called for the Executor's execution, claiming to respect all of Sedriss' decisions. Sedriss retorted that if Sa-Di truly respected his decisions, he would approve of Sedriss' decision to execute him.
Sedriss cleaved Sa-Di in two with a powerful downward strike.
Outcome
With the two betrayers dead, Palpatine revealed his presence. Having inhabited a new clone body, he praised Sedriss's actions, expressing satisfaction that at least one of his subordinates had remained loyal. Palpatine then ordered the capture of Leia Organa Solo and her unborn child, and disclosed that he had planned some surprises for the rebellion.