Guardian of Misthollow dungeon

Whenever a creature enters the battlefield, each player gains life equal to its power, then put an artifact token onto the battlefield named Metal fog, it has: "Sacrifice Metal fog: Exile all spells and prevent all combat damage until end of turn"
"Legend said it had not moved in many centuries. And yet when I watched it though its misty hideout, I heard the groans of its rusted armor moving once more... Something has happened"
-Tamiyo