The first Spinjitzu master, a man of unknown origin or name. The man who created Ninjago itself with the golden weapons. This is just what they want you to think.
The question is, how did the first Spinjitzu master die? Why didn't Sensei Wu include any specific details of his death? This is simply because he did not die. He faked his own death, so he could plot against the ninja, and gain total supremacy.
Samukai, former king of the Underworld, was killed off in the final episode of season 1. This was a method used by the first Spinjitzu master so he could kill off all of his associates used in his plan. Yes, Samukai was one of his associates. The first Spinjitzu master would kill off all of his associates, so they wouldn't gain any thoughts of a rebellion against him.
As we all know, Samukai was the king of the Underworld. With no king, it wouldn't be ruled by anyone. This automatically makes the Underworld claimed and taken over by the first Spinjitzu master.
Later on, when Lloyd Garmadon unleashed the Serpentine on Ninjago, why weren't the tombs locked? Why were they open so any passing individual could just open them? This was because they were already opened, and that the Serpentine and the first Spinjitzu master was already plotting together for this. In fact, this can explain why the Serpentine would be so ready for such a random occurrence. It was already pre-meditated a long time ago.
Another question is: Why would the Serpentine help the first Spinjitzu master's obscure plan? It was simply because the first Spinjitzu master already had full control of the Serpentine long before they were locked away.
Pythor. P. Chumsworth, the "last" Anacondrai, was yet another associate of the first Spinjitzu master's plan. He would carry out all of the first Spinjitzu master's dirty work, as well as serve as a distraction for the ninja, so that his operation can proceed.
In the episode, "Rise of the Great Devourer", Pythor is eaten by the Devourer as well as Sensei Wu. This the second time an associate of the first Spinjitzu master was killed off. An explanation for this is because, the first Spinjitzu master convinced Pythor that unleashing the Great Devourer was the ultimate and only option in ruling Ninjago. Let's list off all the possible reasons what this meant, so we can better identify what was the first Spinjitzu master's intention.
1: Pythor was only used as a pawn in the plan, and was meant to be killed off.
2: Pythor grew more aggressive, so to avoid potential rebellion, he was killed off in Ouroborus.
3: Wu was supposed to be the one killed off in that scene, but Pythor was accidentally eaten because they were in the same position.
Honestly, I have to say that 1 or 2 are the most probable. This would mean that the first Spinjitzu master ultimately used the Devourer to finish Pythor, as that was his planned death location. Sensei Wu was meant to be finished by the Devourer, along with Pythor, so that the first Spinjitzu master would finish Lord Garmadon at the end, in order for his plan to have no obstacles in the way.
After that, Wu miraculously survived, after the Devourer blew up into green goo from Lord Garmadon's attack.
It is strange that Pythor didn't survive after the Devourer's death.
The entire fight in the Ninjago storyline was never between Lord Garmadon and the ninja, but with the first Spinjitzu master and the ninja. Lord Garmadon was only another pawn of the plan.
You see, Lord Garmadon at a very young age, got bit by the Devourer and turned evil. The first Spinjitzu master was there, and saw the entire thing because he created the Devourer. It was created in order for Lord Garmadon to serve as an intentional distraction for the ninja in the future.
Now it would appear that the first Spinjitzu master is trying to make Lloyd Garmadon believe he is the "green ninja", so that he would overthrow Lord Garmadon, and later on, his future associates. This will potentially be the third time he's betrayed his associates in order for his plan to work.
Lloyd, being the first Spinjitzu master's biggest and most important pawn in the game, is now being used to destroy Lord Garmadon. Perhaps, Lloyd will be overthrown at the end.
This may be what the first Spinjitzu master's past associates (Pythor and Samukai) realized, and were trying to warn the ninja about, before being ultimately being betrayed and executed.
Naturally, if the first Spinjitzu master plotted that the Devourer to kill the ninja in the first place, it would be happy to finish them off. Perhaps Lloyd was meant to be killed off by the Devourer as well, or maybe even Lord Garmadon...
Either way, if Lloyd was meant to die or live, what does the first Spinjitzu master want to do afterwards? This may later be revealed in future episodes as the story progresses...
He either wants Lloyd to kill Lord Garmadon, so he could finish off Lloyd afterwards and have all the land for himself. Or he meant to kill Lloyd in Pythor's death place, and is now plotting against him.
Now we have to ask, what would the first Spinjitzu master do if he succeeded?
Pythor and Samukai weren't villains at all, as they could have potentially helped the ninja realize what was going on, as they could have been Ninjago's last hope. The ninja needed their help to save Ninjago.
Because if the first Spinjitzu master needed the help of the Devourer and the weapons to eliminate Pythor and Samukai, than he obviously couldn't do it himself, and that they could possibly show some potential significance. So if Samukai or Pythor weren't killed off, all of this wouldn't have happened.
If all of this never happened, Ninjago would have been saved...