It's a chance to get on a new server with a different character

As you can see from Twitch overlay (below) the timeline was an average of 138 hours for him to go from the level of one to 99. It's harder to climb the levels with each level - making up the last level that he needed to complete to reach 99 took more than a day. Teo1904 says he had 34 hours of rest during the marathon grind.

It took the streamer about eight days to hit level 99. This equates to about five hours of rest each night. It's a credit to him for getting some winks, though. There have been instances of Apex Legends and League of Legends streamers reach their maximum rank of zero on single streams. It's awful.

Teo1904 didn't reach the mark on his own, but he did it with the help of others. Teo1904 had the assistance of friends MacroBioBoi, BTNeandertha1, Rob2628, Jymnasium, Raxxanterax and many others, with the team making use of various strategies to enhance the grind. One of the most touching aspects, however, stems from the name Teo1904's character. As MacroBioBoi writes on Reddit, the 'Unsullied' in 'Teo_Unsuillied' is a reference to dear friend who passed in the last year.

If you've been out in the game for a while, Ladders are Diablo 2's combat game. It's a chance to get on a new server with a different character to play against other players in various modes, which have leaderboards for each. There's also content specific to Ladder like new Rune Words, Cube Recipes and many other items.