Operation B: Tempered Shield is the second operation of Halo: Spartan Assault.
Missions
Transcript
As Spartan Davis continued fighting on the moon, Spartan Palmer and a handful of UNSC troops redeployed to the surface of Draetheus-V to fend off the invaders there.
Outmanned? outgunned?
Spartan Palmer didn't see it as a problem.
How about you?
Trivia
The level is probably named in reference to the "Sharpened Shield", an alternate name for Shield World 006, which actually stems from a misunderstanding on Halopedia.