Celestial Armor
Artifact — Equipment
Flash (You may cast this spell any time you could cast an instant.)
When this Equipment enters, attach it to target creature you control. That creature gains hexproof and indestructible until end of turn.
Equipped creature gets +2/+0 and has flying.
Equip 
(: Attach to target creature you control. Equip only as a sorcery.)
José Parodi
Foundations (FDN)
• #364Rulings
If a creature gains hexproof in response to a spell or ability controlled by an opponent that only targets that creature, then when that spell or ability tries to resolve, all of its targets will be illegal. As a result, that spell or ability won't resolve and none of its effects will happen.
(wotc • 2024-11-08)
Attaching Celestial Armor to a creature that has already been blocked won't cause it to become unblocked, even if one or more of the blocking creatures don't have flying or reach.
(wotc • 2024-11-08)
Rulings
If a creature gains hexproof in response to a spell or ability controlled by an opponent that only targets that creature, then when that spell or ability tries to resolve, all of its targets will be illegal. As a result, that spell or ability won't resolve and none of its effects will happen.
(wotc • 2024-11-08)
Attaching Celestial Armor to a creature that has already been blocked won't cause it to become unblocked, even if one or more of the blocking creatures don't have flying or reach.
(wotc • 2024-11-08)