Their death for your life. Their humiliation for our glory. Do not fail us.
We exist in a multiverse controlled by gods. The gods create, control, and destroy life in these universes. The gods of different universes enjoy pitting their sentient life forms against each other in trials of combat.
These contests consist of 18 champions from two different races, and the gods watch as their creations fight to the death.
After a Crucible, the losing race is annihilated, and their gods create a new form of intelligent life. Humanity has survived the Crucibles longer than most other races.
We have won and survived for 200,000 years, and our gods are getting bored.