Yep...when a team takes the six keeps circling the lake they are awarded SUPREME AND UNENDING RULE OF CYRODIIL. Or, at least until another team takes it back.

When a team wins emperor, whomever is top on the leaderboard is crowned, the top being earned by total AP during that campaign.

I wish they'd devise a new system. Emperor should be rare and hard to get, but it's only available to AP farmers. In Scourge right now on PS4 NA, about 2 weeks into the campaign, the leaders have about 9 million AP. I'd propose that maybe emperorship is opened up to the top ten on a team's leaderboard, determined by RNG. That's still very exclusive, and takes a lot of AP to qualify, but would open the perk to people who are actually fighting and not just AP farmers...many who account share.