It acts like a creature, but only temporarily
Ross, Hapless Attach Falcon and Redwing Hatut Zeraze Strike Force Hercules, Olympian Hero Heroic Return Heroic Sacrifice Invisible Force Field King Solomon's Frogs Methods of the Mighty Midnight Angel Armor Queen Mother Ramonda Royal Talon Fighter Jet The Spear of Bashenga Ultimate Nullification Winter Soldier, Reborn Avenger Council of Reeds Extract Power Fantastic Elasticity Glorious Purpose Helmut Zemo, Mastermind Iron Man, Armored Avenger Jarvis, Earth's Mightiest Butler Kang Dynasty Lockjaw, Slobbering Teleporter Professor Hulk Valeria Richards, Precocious The Wasp, Winsome Avenger West Coast Expansion Age of Ultron Damocles Base, Sword of Kang Endless Ranks of HYDRA The Frightful Four Iron Monger, Sadistic Tycoon Klaw, Master of Sound Abomination, World Ravager Alicia Masters, Skilled Sculptor Batroc the Leaper Firebird, Blazing Ranger Flame On
If either creature is an illegal target as Knockout Maneuver resolves, the creature you control won't deal damage
You can use it to save stuff from mass removal or targeted, protect something post-bounce, and a lot more
Oh, yes, and it has limited uses for swapping blockers
Some even do have card quality, card draw or direct mana fixing attached to them