In some versions, it could be a former ally who has been corrupted. This character, once on Ahsoka's side, has now turned against her due to some external influence or personal greed. Their knowledge of Ahsoka's strengths and weaknesses would make them a formidable opponent, and they could be the one to cause her death.
Her opponents could be the Separatist forces. Umbara was a planet involved in the Clone Wars, so it's likely that battle droids and their commanders would be her foes. They would be trying to gain control of Umbara's resources or strategic locations.
In a 'ahsoka death fanfic', one possible scenario could be her sacrificing herself in a battle against a powerful enemy. Maybe she faces an overwhelming force that she decides to take on alone to protect others.
It could also be that she contracts a deadly disease in a far - flung part of the galaxy. Since she travels so much, she might come into contact with a new and unknown pathogen. Despite her Jedi training and resilience, this disease could be too much for her body to handle, and she slowly succumbs to it.
A new villain could be introduced in the fanfic who is specifically out to get Connor Kenway. This villain might have a personal grudge against Connor or be on a mission to eliminate all the Assassins, and Connor becomes their prime target and ultimately falls to their schemes.
Perhaps in a more complex scenario, Ahsoka could be trapped in a time - loop that is slowly draining her life force. She tries to break free but realizes that the only way to stop the loop from spreading and destroying everything is to give up her own life. This would be a very tragic and thought - provoking way to write her death in a fanfiction.
Her friends like Rex would be heartbroken. He has fought alongside her for so long. Her death would make him feel like he has lost a part of his family. He might become more withdrawn or even more determined to fight in her memory.
Perhaps it was a result of friendly fire or a mistake by an ally. This would add an interesting layer of drama and conflict, especially if there are trust issues that need to be resolved.
It could be a Sith or a Sith - inspired enemy. They are often the ones causing trouble for the Jedi, and shooting Ahsoka would be a way to strike at the Jedi Order.
The villagers themselves could be responsible. Their constant ostracization and negative treatment of Naruto could lead to his downfall. He might be pushed to a point where he takes risks that ultimately cost him his life.
Another possibility is a former crewmate turned traitor. This crewmate could have been jealous of Edward's leadership and the share of the loot he got. So, the traitor could plot with other pirates or even the enemy. They could stage a mutiny at a crucial moment, like when they are about to face a big battle or are in the middle of a difficult sea journey. During the mutiny, the former crewmate could be the one to deliver the fatal blow to Edward.