From Exterminatus Manual
Whenever you ++
Whenever you die in Exterminatus you get the chance to pick a new class, based on the points you have earned during the game. Capturing and destroying Objectives, or wounding enemies earns you reward points. More expsensive classes give greater rewards when wounded. Once you have earned enough points for the most powerfull cless available to your team any further points are distributed to your team. You can see how many points you have earned during this spawn and during the duration of the round (score) on the scoreboard which is bound to the tab key by default. When your new class has been selected you must wait for your team's "spawn wave", a timer at the top of the screen should tell you how long you have to wait to be spawned, your team's misison will also be stated at the bottom of the screen.
Server operators can set wait the period at the console using the variable ex_respawn_wave_length.
Dead members of your team then get a short period to spawn, controlled by the server console variable ex_respawning_time. Dead players are automatically spawned at their teams objective during this time, so if you're Away From Keyboard (AFK) best disconnect from the server.
The idea behind this is to keep the team together and spawn as many players together at once to prevent spawn camping.gation'>