The Attack on Teacher's Compound

 is the event in which the heroes attempted to take Teacher down.

Prelude
Antares and Tattletale uncovered a plot by Teacher to subtly undermine all the heroes by spying on them, and planting false information that would serve to screw them over. After bringing this to the Wardens, the heroes decided to band together and take Teacher on in his home base.

Events
The base is invaded, and several fights break out between the heroes and the thralls who work under Teacher.

Breakthrough and company fight their way through the base, taking on several enemies, including The Leper, a Syringe Shaker, the Dragonslayers, remnants of the Fallen, and the Speedrunners.

The team breaks Contessa out of custody, and she sets them on a path to defeating Teacher, albeit with several negative consequences.

On this path, Precipice kills Valefor and saves Chevalier from Mama Mathers, Tress takes out the Dragonslayers, Byron is critically injured by Secondhand, and Ashley is killed in a fight with Ingenue and Spawner.

The heroes track Teacher down and discover that he has opened a portal to the Shardspace. They arrest him, but he manages to escape with an undercover thrall, taking Legend with him.