Swiftfoot Boots
Artifact — Equipment
Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and 
no matter when it came under your control.)
Equip 
(: Attach to target creature you control. Equip only as a sorcery.)
Svetlin Velinov
Foundations (FDN)
• #258Rulings
If a creature enters the battlefield under your control and gains haste, but then loses it before attacking, it won't be able to attack that turn. This means that you can't use one Swiftfoot Boots to allow two new creatures to attack in the same turn.
(wotc • 2018-03-16)
Rulings
If a creature enters the battlefield under your control and gains haste, but then loses it before attacking, it won't be able to attack that turn. This means that you can't use one Swiftfoot Boots to allow two new creatures to attack in the same turn.
(wotc • 2018-03-16)