A group of [Champion] is called a…

Legion Skulk Shroud Herd Wrap Blizzard Class Quiver or pile Galaxy House or dynasty Band Scrap Pyre Safeguard Force Protocol Constellation, bed, or nest Terror Squadron Hand Satellite Rouleau Draven Echo, dilation, or continuum Cluster Embrace Museum Murder Foil School Cathedral Parley Bush Rage Cask Yard Cavalry Dong Convention Nerf Joint Gale Standard Post Forge Theater Riot Kalista (see lore) Sae eleisA TERA VI Choir Muffle Clowder, apparently Salad Storm Swarm Kindred First Legion Third Multiplication Artillery Vanguard Company Second Legion Artillery-Cavalry Multiplication Stomach Mirage Fold Primary Tomb Sling Twirl Rainbow Mountain Infection Forest Strike Spine Malice Snare Pool Library Reef Twihard, apparently Dream anxiety disorder Willump Shirt Clock Phalanx Keep Squad Muster Roll Pack Fury Hunt Kindergarten Quake Scroll Tribe Circus Multitude (see the Multi Shen Theory Thunder Contamination Train Flock, brace, raft, team, or paddling Nest Harmony Bunch Flock Ball Bargain Volley Claw Glimmer Horde Lantern Pocket Trolley Arm Deck Mischief, apparently Pelt Impossibility Pant Weather station Stack Tent Gauntlet Innocence Clot Sleuth, apparently Hunger Troop Plumage Bolt Sweep Tumor Cape or cemetery Bounce Mark Minefield Timeline Garden

Some of these are probably bad, so please give suggestions. Thanks to Velzard of Koz and mkyner. Oh, and I'm trying not to repeat anything, so if you give a suggestion that would replace something, come up with another suggestion. Or I'll just work it out, I dunno.