Enchantment, 2R (3)
Rare
Creatures you control have haste. (They can attack and {T} as soon as they come under your control.)
The intensity of their glare was soon surpassed by the intensity of their attack.
Illus. Wayne England

7/1/2012: If an attacking creature loses haste, perhaps because Fervor leaves the battlefield after attackers have been declared, it won't be removed from combat.
Legal in Vintage (Type 1)
Legal in Legacy (Type 1.5)
Legal in Extended (Type 1.X)
Legal in Standard (Type 2)
Legal in Classic (MTGO)
Legal in Commander
Legal in Modern