" In a time before time, there was a Skull Spider. It was on his way to the City of the Mask Makers to get the Mask of Creation along with about over 9000 other Skull Spiders under Makuta’s will.
When it arrived, It immediately spotted the Mask it was after. It then leaped at it with all it's might, but when it touched the Mask, the most unexpected thing happened. It grew in size and shape, obtaining spikes, teeth, more eyes, and an extra two legs. Unfortunately, it quickly realized that the rest of the Skull Spiders were getting obliterated by Kulta and his massive army of warriors. The soon to be Lord of Skull Spiders then turned and ran.
Much later, after the clash between the two brothers, a mask was left at the battle sight. It was the Mask of the Skull Spiders. LoSS then claimed it, becoming the Lord of the Skull Spiders that we all know and love today.
A few hundred years later, a Skull Spider reported to LoSS that the Mask of Creation was in the City of the Mask Makers. It was also told about the prophecy and that once the heroes entered the city, the city would come back to life. This meant that Kulta and his army would be revived. To prevent this, LoSS began to guard the only way into the city so that once the heroes were eliminated, it could go and claim the Mask of Creation."
Fast forward to the animations.