Serion of the dusk

Sacrifice Serion of the dusk at the end of your turn.
If you have 7 or more swamps out at the beginning of your upkeep, put Serion of dusk onto the battlefield from your graveyard.
If Serion of the dusk enters the battlefield from your graveyard, he deals 3 damage to target creature or player, he gains flying and haste until end of turn.