Prismatic Ending — ruling 1

You can choose any value for X. Choosing a higher value for X lets you pay more mana and thus spend more colors of mana to cast it. For example, if you choose 0 for the value of X and pay {W} to cast Prismatic Ending, you can exile a nonland permanent with mana value 0 or 1. If you choose 4 for the value of X and pay {W}{U}{B}{R}{G}, you can exile a nonland permanent with mana value 5 or less.

Prismatic Ending — ruling 2

The maximum number of colors of mana you can spend to cast a spell is five. Colorless is not a color. Note that the cost of a spell with converge may limit how many colors of mana you can spend.

Prismatic Ending — ruling 3

Unless a spell or ability allows you to, you can't choose to pay more mana for a spell with a converge ability just to spend more colors of mana. Likewise, if a spell or ability reduces the amount of mana it costs you to cast a spell with converge, you can't ignore that cost reduction in order to spend more colors of mana.

Prismatic Ending — ruling 4

If there are any alternative or additional costs to cast a spell with a converge ability, the colors of mana spent to pay those costs will count.

Prismatic Ending — ruling 5

If you cast a spell with converge without spending any mana to cast it (perhaps because an effect allowed you to cast it without paying its mana cost), then the number of colors spent to cast it will be zero.

Prismatic Ending — ruling 6

The mana value is not a targeting condition. It is checked only as the spell resolves.

Prismatic Ending — ruling 7

If a spell with a converge ability is copied, no mana was spent to cast the copy, so the number of colors of mana spent to cast the spell will be zero. The number of colors spent to cast the original spell is not copied.

Prismatic Ending : règles, fonctionnement et interactions (MTG)

Prismatic Ending is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Converge — Exile target nonland permanent if its mana value is less than or equal to the number of colors of mana spent to cast this spell.

How it works : Prismatic Ending

Original English text — Wizards of the Coast / Scryfall

#1June 18, 2021· Wizards of the Coast
You can choose any value for X. Choosing a higher value for X lets you pay more mana and thus spend more colors of mana to cast it. For example, if you choose 0 for the value of X and pay to cast Prismatic Ending, you can exile a nonland permanent with mana value 0 or 1. If you choose 4 for the value of X and pay , you can exile a nonland permanent with mana value 5 or less.
No other card is named in this ruling.
#2June 18, 2021· Wizards of the Coast
The maximum number of colors of mana you can spend to cast a spell is five. Colorless is not a color. Note that the cost of a spell with converge may limit how many colors of mana you can spend.
No other card is named in this ruling.
#3June 18, 2021· Wizards of the Coast
Unless a spell or ability allows you to, you can't choose to pay more mana for a spell with a converge ability just to spend more colors of mana. Likewise, if a spell or ability reduces the amount of mana it costs you to cast a spell with converge, you can't ignore that cost reduction in order to spend more colors of mana.
No other card is named in this ruling.
#4June 18, 2021· Wizards of the Coast
If there are any alternative or additional costs to cast a spell with a converge ability, the colors of mana spent to pay those costs will count.
No other card is named in this ruling.
#5June 18, 2021· Wizards of the Coast
If you cast a spell with converge without spending any mana to cast it (perhaps because an effect allowed you to cast it without paying its mana cost), then the number of colors spent to cast it will be zero.
No other card is named in this ruling.
#6June 18, 2021· Wizards of the Coast
The mana value is not a targeting condition. It is checked only as the spell resolves.
No other card is named in this ruling.
#7June 18, 2021· Wizards of the Coast
If a spell with a converge ability is copied, no mana was spent to cast the copy, so the number of colors of mana spent to cast the spell will be zero. The number of colors spent to cast the original spell is not copied.
No other card is named in this ruling.