The manifested card was Ghalta, Stampede Tyrant. They exiled it with Hide on the Ceiling, probably during the second main phase of your turn 3. It returned face up in your end step. Face up is the default for permanents to enter, and nothing here says that it would enter otherwise. And since it entered the battlefield, its ETB trigger went off, allowing your opponent to put any number of creature cards from their hand onto the battlefield. That were Armaggon, and Raph & Mikey. On their turn 4 they attacked with all of them, triggering Raph and Mikey, which got them the Ancient Adamatoice attacking, too.