Bring to Light — ruling 1

If there are any alternative or additional costs to cast a spell with a converge ability, the mana spent to pay those costs will count. For example, if an effect makes sorcery spells cost {1} more to cast, you could pay {W}{U}{B}{R} to cast Radiant Flames and deal 4 damage to each creature.

Bring to Light — ruling 2

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.

Bring to Light — ruling 3

If you cast a card "without paying its mana cost," you can't choose to cast it for any alternative costs, such as awaken costs. You can, however, pay additional costs, such as kicker costs. If the card has any mandatory additional costs, you must pay those to cast the card.

Bring to Light — ruling 4

If the card has {X} in its mana cost, you must choose 0 as the value of X.

Bring to Light — ruling 5

If you cast the exiled card, you do so as part of the resolution of Bring to Light. You can't wait to cast it later in the turn. Timing restrictions based on the card's type are ignored, but other restrictions (such as "Cast [this card] only during combat") are not.

Bring to Light — ruling 6

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.

Bring to Light — ruling 7

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.

Bring to Light — ruling 8

If you don't cast the card, it remains exiled.

Bring to Light : règles, fonctionnement et interactions (MTG)

Bring to Light 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 — Search your library for a creature, instant, or sorcery card with mana value less than or equal to the number of colors of mana spent to cast this spell, exile that card, then shuffle. You may cast that card without paying its mana cost.

How it works : Bring to Light

Original English text — Wizards of the Coast / Scryfall

#1August 25, 2015· Wizards of the Coast
If there are any alternative or additional costs to cast a spell with a converge ability, the mana spent to pay those costs will count. For example, if an effect makes sorcery spells cost more to cast, you could pay to cast Radiant Flames and deal 4 damage to each creature.
No other card is named in this ruling.
#2August 25, 2015· 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.
#3August 25, 2015· Wizards of the Coast
If you cast a card "without paying its mana cost," you can't choose to cast it for any alternative costs, such as awaken costs. You can, however, pay additional costs, such as kicker costs. If the card has any mandatory additional costs, you must pay those to cast the card.
No other card is named in this ruling.
#4August 25, 2015· Wizards of the Coast
If the card has in its mana cost, you must choose 0 as the value of X.
No other card is named in this ruling.
#5August 25, 2015· Wizards of the Coast
If you cast the exiled card, you do so as part of the resolution of Bring to Light. You can't wait to cast it later in the turn. Timing restrictions based on the card's type are ignored, but other restrictions (such as "Cast [this card] only during combat") are not.
No other card is named in this ruling.
#6August 25, 2015· 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.
#7August 25, 2015· 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.
#8August 25, 2015· Wizards of the Coast
If you don't cast the card, it remains exiled.
No other card is named in this ruling.
#9August 25, 2015· Wizards of the Coast
If you cast an instant or sorcery card this way, it goes to your graveyard as normal. It doesn't return to exile.
No other card is named in this ruling.
#10August 25, 2015· 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.