Complex sentence: The site's flagship weekly event is the "Sunday Million", a weekly tournament with a guaranteed $1 million prize pool with a buy-in of $215 and is the biggest weekly online poker tournament in the world.
Split into simpler sentences: The site's flagship weekly event is the "Sunday Million", a weekly tournament with a guaranteed $1 million prize pool and a $215 buy-in. The Sunday Million and is the biggest weekly online poker tournament in the world.