Maul of the Skyclaves
Artifact — Equipment
When this Equipment enters, attach it to target creature you control.
Equipped creature gets +2/+2 and has flying and first strike.(It deals combat damage before creatures without first strike.)
Equip
Joseph Meehan
Rulings
If the target creature becomes an illegal target, the Equipment remains on the battlefield unattached.
(wotc • 2020-09-25)
Attaching an Equipment with its enters-the-battlefield triggered ability isn't the same as using its equip ability. You don't pay mana for the attachment, and if the Equipment enters at a time you couldn't cast a sorcery, you can still attach it to a creature you control.
(wotc • 2020-09-25)
Rulings
If the target creature becomes an illegal target, the Equipment remains on the battlefield unattached.
(wotc • 2020-09-25)
Attaching an Equipment with its enters-the-battlefield triggered ability isn't the same as using its equip ability. You don't pay mana for the attachment, and if the Equipment enters at a time you couldn't cast a sorcery, you can still attach it to a creature you control.
(wotc • 2020-09-25)