I thought that Kaelidoscope needed to have 1/6 of each colour.
Cathaldus, were you thinking of Rainbow/Spectial Stairwell? Where your spells have to fit the following guidelines (translated by me)
At least 1 white card at CMC of :1mana:.
At least 1 blue card at CMC of :1mana:.
At least 1 black card at CMC of :1mana:.
At least 1 red card at CMC of :1mana:.
At least 1 green card at CMC of :1mana:.
Repeat this process at CMC of :2mana:, :3mana:, :4mana:, :5mana: and :6mana:. This makes for 30 specific cards in your deck.
You must also have 6 land that produce

.
You must also have 6 land that produce

.
You must also have 6 land that produce

.
You must also have 6 land that produce

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You must also have 6 land that produce

.
Or else there is Prismatic, which is 250 cards and five colours.