"Magical Hats":

Yu-Gi-Oh!

The artwork initially features black hats and a white glow. This is later changed to blue hats and a pink glow.
In the Yu-Gi-Oh! anime, Magical Hats was a Quick-Play Spell Cards with the lore: "Activate only if you control a face-up Spellcaster-Type monster. Select 1 monster you control and flip it into face-down Defense Position. Special Summon 3 "Magical Hat Tokens". The face-down cards are then shuffled. Trap Cards may be Set to be triggered when one of the Tokens is destroyed." (In the real card game this card is a Trap Card, not a Spell Card.)
This card first appeared in episode 009, where it was used to hide Yugi's Dark Magician from Ghost Kaiba's Blue-Eyes White Dragon. However, this was not elaborated on until episode 010, where the Mimic misses the Dark Magician twice, triggering Spellbinding Circle on the second shot.
Yugi uses this card against the Paradox Brothers.
Yugi uses this card against Joey Wheeler in Yu-Gi-Oh! - Episode 34.
Yugi uses this card against Maximillion Pegasus.
Yugi uses this card in the Virtual World in Yu-Gi-Oh! - Episode 44.
Yugi uses this card against Bandit Keith in Yu-Gi-Oh! - Episode 51.
Yugi Muto used this card to protect his Dark Magician from Arkana's Mystic Guillotine.
Yami Marik uses this card in Yu-Gi-Oh! - Episode 139.
This card can be seen in Yugi's hand after he activates Card of Sanctity during episode 157.
This card is used in Episode 175 to protect Big Shield Gardna and Dark Magician from Rafael's Guardian monsters.

Yu-Gi-Oh! GX

This card appears in the GX Japanese closing song Borderline Battle as a Spell Card.
This card can be seen in episode 180 in Yugi's hand after Subspatial Battle resolves.