Havoc Harbinger

At the beginning of each player's upkeep,
they discard a card and exile the top card of their library face-down.
({3}{p/u}{p/b}{p/r}): Exile Havoc Harbinger. Each player shuffles their hand and graveyard into their library, then draws seven cards.
Until the end of turn, players may play cards
exiled with Havoc Harbinger without paying their mana costs.