Ascension refers to rule 6b of The Book of Blaseball, which states "If a team wins three championships, they, and Blaseball, shall ascend." As of the end of Season 10, the Baltimore Crabs are the only team to have ascended.
Ascension was first revealed at the end of Season 1 when The Forbidden Book was opened and revealed to be a highly redacted rulebook. Rule 6b was quickly noticed for its clarity among dozens of vague and redacted entries.
In Season 3 and Season 4, the Hades Tigers won both championships back to back, becoming the second team to be eligible for Ascension with the next victory. At the time, both the Pies and the Tigers were in the Evil League, making only one of the two teams eligible for any given Internet Series.
The next team to be eligible for Ascension was the Baltimore Crabs, who won the Internet Series in Season 6 and Season 8. The Crabs made it to the Internet Series in Season 9, but were thwarted by the Charleston Shoe Thieves.
In Season 10, the Baltimore Crabs defeated the Charleston Shoe Thieves in a rematch in the Internet Series, in a 3 game sweep. Immediately following, the Crabs faced off against The Shelled One in Day X. The Shelled One had some words for the three-time champions:
THIS IS YOUR CHAMPION?
YOU BELIEVE YOU ARE WORTHY
TO GO UP?
The Crabs were then instantly defeated by THE SHELLED ONE'S PODS, however, the Shelled One left some hints as to what Ascension entailed for the Crabs.
LET THIS BE A LESSON
THE BIG LEAGUES ARE CALLING
The next day, as a part of the Season 10 election results, the League learned that the Crabs had been "Called Up" and replaced in the ILB by the Tokyo Lift. The Baltimore Crabs were no longer listed as an active team in the Wild League and would not be participating in Season 11.
At the start of Season 11, however, a new tracker appeared on the Blaseball Bulletin, called Telescope, that displayed a win-loss record for the Crabs in the Big Leagues, with the Crabs having posted majority losses. An issue of The Blaseball Beat released that covered the events of Season 10 asked readers, "Wait a minute where ARE the Crabs?"
About a quarter of the way through Season 11, the groundskeepers (Discord server moderators) discovered the location of the Baltimore Crabs, and along with it, the 1-Blood Blagonball. The location of the Crabs appeared to be at a sort of Gateway in the clouds, with a second, red gate blocking the exit of the Crabs. The newly-promoted CEO Commissioner Prime Minister Parker MacMillan III clarified in a tweet, "The Crabs are playing. The Big Leagues are not for your viewing pleasure. Our Optics extend as far as the Gateway 🩸⚾"