Dark Apostle — ruling 1

As Dark Apostle's activated ability resolves, it creates a continuous effect that won't begin to apply until you start casting a noncreature spell this turn. It applies to that spell and the timestamp of that effect is the time that the spell was put on the stack.

Dark Apostle — ruling 2

If you activate the ability of more than one Dark Apostle (or the same one more than once) in the same turn, the next noncreature spell you cast will have that many instances of cascade, each of which will trigger separately.

Dark Apostle — ruling 3

See also "Returning Keyword Ability: Cascade" in the General Notes section.

Dark Apostle — ruling 4

A spell's mana value is determined only by its mana cost. Ignore any alternative costs, additional costs, cost increases, or cost reductions.

Dark Apostle — ruling 5

Cascade triggers when you cast the spell, meaning that it resolves before that spell. If you end up casting the exiled card, it will go on the stack above the spell with cascade.

Dark Apostle — ruling 6

When the cascade ability resolves, you must exile cards. The only optional part of the ability is whether or not you cast the last card exiled.

Dark Apostle — ruling 7

If a spell with cascade is countered, the cascade ability will still resolve normally.

Dark Apostle — ruling 8

You exile the cards face up. All players will be able to see them.

Dark Apostle : règles, fonctionnement et interactions (MTG)

Dark Apostle 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

Gift of Chaos — , : The next noncreature spell you cast this turn has cascade. (When you cast that spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

How it works : Dark Apostle

Original English text — Wizards of the Coast / Scryfall

#1October 7, 2022· Wizards of the Coast
As Dark Apostle's activated ability resolves, it creates a continuous effect that won't begin to apply until you start casting a noncreature spell this turn. It applies to that spell and the timestamp of that effect is the time that the spell was put on the stack.
No other card is named in this ruling.
#2October 7, 2022· Wizards of the Coast
If you activate the ability of more than one Dark Apostle (or the same one more than once) in the same turn, the next noncreature spell you cast will have that many instances of cascade, each of which will trigger separately.
No other card is named in this ruling.
#3October 7, 2022· Wizards of the Coast
See also "Returning Keyword Ability: Cascade" in the General Notes section.
No other card is named in this ruling.
#4October 7, 2022· Wizards of the Coast
A spell's mana value is determined only by its mana cost. Ignore any alternative costs, additional costs, cost increases, or cost reductions.
No other card is named in this ruling.
#5October 7, 2022· Wizards of the Coast
Cascade triggers when you cast the spell, meaning that it resolves before that spell. If you end up casting the exiled card, it will go on the stack above the spell with cascade.
No other card is named in this ruling.
#6October 7, 2022· Wizards of the Coast
When the cascade ability resolves, you must exile cards. The only optional part of the ability is whether or not you cast the last card exiled.
No other card is named in this ruling.
#7October 7, 2022· Wizards of the Coast
If a spell with cascade is countered, the cascade ability will still resolve normally.
No other card is named in this ruling.
#8October 7, 2022· Wizards of the Coast
You exile the cards face up. All players will be able to see them.
No other card is named in this ruling.
#9October 7, 2022· 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. You can, however, pay additional 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.
#10October 7, 2022· Wizards of the Coast
If the card has in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.
No other card is named in this ruling.
#11October 7, 2022· Wizards of the Coast
Due to a 2021 rules change to cascade, not only do you stop exiling cards if you exile a nonland card with lesser mana value than the spell with cascade, but the resulting spell you cast must also have lesser mana value. Previously, in cases where a card's mana value differed from the resulting spell, such as with some modal double-faced cards or cards with an Adventure, you could cast a spell with a higher mana value than the exiled card.
No other card is named in this ruling.
#12October 7, 2022· Wizards of the Coast
Two new cards in this set give the next spell you cast cascade. This means that the next spell you cast gains cascade as you begin to cast it by putting it on the stack, and the cascade ability will trigger when you finish casting that spell.
No other card is named in this ruling.