From the High Speed Halo news post:
“Two new runs have been added to The Unique Runs Page this week. The Heretic Leader Battle in 1:20 and The Co-op Tartarus Battle in 2:12.
Sczee puts his Sword-Flying skills to good use by following the Heretic Leader into the ceiling vents. Just so you know, the Heretic Leader cannot take damage while he is talking.
The Co-op Tartarus Battle is from themann1086 and IrishMann313. In this battle Player 1 first provides sniper cover for Player 2, then switches to aerial cover.”
Heretic Leader Battle
Rules: Filming must start from the checkpoint after the cutscene that triggers when you enter the boss room, and must continue until a few seconds into the cutscene after the Heretic Leader dies. The Fuel Rod Gun from the previous level cannot be carried-over.