Mocking Sprite
Creature — Faerie Rogue
Flying
Instant and sorcery spells you cast cost 
less to cast.
"Look at me, everyone! I'm a High Fae! Watch me do important High Fae things!"
Ben Hill
Foundations (FDN)
• #159Rulings
Mocking Sprite's last ability can't reduce the amount of colored mana you pay for a spell. It reduces only the generic mana component of that cost.
(wotc • 2023-09-01)
Mocking Sprite's last ability doesn't change the mana cost or mana value of any spell. It changes only the total cost you pay.
(wotc • 2023-09-01)
Rulings
Mocking Sprite's last ability can't reduce the amount of colored mana you pay for a spell. It reduces only the generic mana component of that cost.
(wotc • 2023-09-01)
Mocking Sprite's last ability doesn't change the mana cost or mana value of any spell. It changes only the total cost you pay.
(wotc • 2023-09-01)