This beta removed the tech requirements for quests, but the Arena of the Slakhanan didn't get the message. It says you need Breon's Letters to enter, but won't let you use it (even if you do research Breon's Letters). Just something to fix in the next update. Also FYI, this is a game that started in original Beta 4, but was updated to .951 then .952.
EDIT: This bug also is present for a new game (and the gates for the Master Quest endspot also seem to use this string).