Helm of the Host is a rare Legendary Artifact — Equipment card from Dominaria Promos (PDOM), collector number 217p. Current market price: $11.94 (foil $18.15), TCGplayer market prices via Scryfall.
At the beginning of combat on your turn, create a token that's a copy of equipped creature, except the token isn't legendary. That token gains haste. Equip {5}