It's hard to say that this is the sub-team that makes the least sense, but easy to say it doesn't make much sense. For starters, which one of these three has a secret affection for French wordplay? In anycase, look both ways and hit the marker to begin.
As usual for a team mission, these three heroes will be raiding a lair together. Break in and get moving. Your first challenge room will be a terminal hack.
Clear that for a showdown with Shocktrooper (your objective text calls him a commander, but he seems to be regular rank and file).
After you've cleared the faux commander and his blitztrooper cronies, you'll skate through a few empty rooms into an ambush with the objective 'Defend Yourself.' As only base level helltroopers attack, this is pretty easy to do.
Hack some more security terminals in the next room, before facing off with another LEGION 'commander' in the room after, this one a tank trooper.
As always, concentrate fire on the massive techno-pustule sprouting from his back. When you've cleared this room, the next is a 'Kill All Enemies' go round- mostly swarmtroopers.
After that, use your scanner to locate and destroy the 20 ice cream maker crates. There are exactly twenty, and you do have to frag them all.
Helltroopers will try to stop you, but when have helltroopers stopped anything? With this plot foiled, make for the final room and take down PB-74.
Like most Pride Captain types, he's a pretty tough cookie- use Daisy to chew through his shields and those of his empowered associates, Braddock to take out his armor, and Yeti for damage mitigation and crowd control. Try to kill him up close, because the moment he dies the mission ends, whisking you away from all his dropped loot, and into a cutscene that ends with mission completion.