Callous Sell-Sword // Burn Together — ruling 1

If the first target of Burn Together is an illegal target as the spell resolves but the last target is still legal, Burn Together will resolve, but no damage will be dealt and nothing will be sacrificed.

Callous Sell-Sword // Burn Together — ruling 2

If the last target of Burn Together is an illegal target as the spell resolves but the first target is still legal, Burn Together will still resolve and you'll still sacrifice the first target.

Callous Sell-Sword // Burn Together — ruling 3

An adventurer card is a permanent card in every zone except the stack, as well as while on the stack if not cast as an Adventure. Ignore its alternative characteristics in those cases. For example, while it’s in your graveyard, Questing Druid is a green creature card whose mana value is 2. It can’t be the target of Tenacious Tomeseeker’s triggered ability (“return target instant or sorcery card from your graveyard to your hand”).

Callous Sell-Sword // Burn Together — ruling 4

When casting a spell as an Adventure, use the alternative characteristics and ignore all of the card’s normal characteristics. The spell’s color, mana cost, mana value, and so on are determined by only those alternative characteristics. If the spell leaves the stack, it immediately resumes using its normal characteristics.

Callous Sell-Sword // Burn Together — ruling 5

If you cast an adventurer card as an Adventure, use only its alternative characteristics to determine whether it’s legal to cast that spell. For example, if you control Johann, Apprentice Sorcerer (“Once each turn, you may cast an instant or sorcery spell from the top of your library.”) and Questing Druid is on top of your library, you can cast Seek the Beast, but not Questing Druid.

Callous Sell-Sword // Burn Together — ruling 6

If a spell is cast as an Adventure, its controller exiles it instead of putting it into its owner’s graveyard as it resolves. For as long as it remains exiled, that player may cast it as a permanent spell. If an Adventure spell leaves the stack in any way other than resolving (most likely by being countered or by failing to resolve because its targets have all become illegal), that card won’t be exiled and the spell’s controller won’t be able to cast it as a permanent later.

Callous Sell-Sword // Burn Together — ruling 7

If an adventurer card ends up in exile for any other reason than by exiling itself while resolving, it won’t give you permission to cast it as a permanent spell.

Callous Sell-Sword // Burn Together — ruling 8

You must still follow any timing restrictions and permissions for the permanent spell you cast from exile. Normally, you’ll be able to cast it only during your main phase while the stack is empty.

Callous Sell-Sword // Burn Together : règles, fonctionnement et interactions (MTG)

Callous Sell-Sword // Burn Together 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

This creature enters with a +1/+1 counter on it for each creature that died under your control this turn. Target creature you control deals damage equal to its power to any other target. Then sacrifice it.

How it works : Callous Sell-Sword // Burn Together

Original English text — Wizards of the Coast / Scryfall

#1September 1, 2023· Wizards of the Coast
If the first target of Burn Together is an illegal target as the spell resolves but the last target is still legal, Burn Together will resolve, but no damage will be dealt and nothing will be sacrificed.
No other card is named in this ruling.
#2September 1, 2023· Wizards of the Coast
If the last target of Burn Together is an illegal target as the spell resolves but the first target is still legal, Burn Together will still resolve and you'll still sacrifice the first target.
No other card is named in this ruling.
#3September 1, 2023· Wizards of the Coast
An adventurer card is a permanent card in every zone except the stack, as well as while on the stack if not cast as an Adventure. Ignore its alternative characteristics in those cases. For example, while it’s in your graveyard, Questing Druid is a green creature card whose mana value is 2. It can’t be the target of Tenacious Tomeseeker’s triggered ability (“return target instant or sorcery card from your graveyard to your hand”).
No other card is named in this ruling.
#4September 1, 2023· Wizards of the Coast
When casting a spell as an Adventure, use the alternative characteristics and ignore all of the card’s normal characteristics. The spell’s color, mana cost, mana value, and so on are determined by only those alternative characteristics. If the spell leaves the stack, it immediately resumes using its normal characteristics.
No other card is named in this ruling.
#5September 1, 2023· Wizards of the Coast
If you cast an adventurer card as an Adventure, use only its alternative characteristics to determine whether it’s legal to cast that spell. For example, if you control Johann, Apprentice Sorcerer (“Once each turn, you may cast an instant or sorcery spell from the top of your library.”) and Questing Druid is on top of your library, you can cast Seek the Beast, but not Questing Druid.
No other card is named in this ruling.
#6September 1, 2023· Wizards of the Coast
If a spell is cast as an Adventure, its controller exiles it instead of putting it into its owner’s graveyard as it resolves. For as long as it remains exiled, that player may cast it as a permanent spell. If an Adventure spell leaves the stack in any way other than resolving (most likely by being countered or by failing to resolve because its targets have all become illegal), that card won’t be exiled and the spell’s controller won’t be able to cast it as a permanent later.
No other card is named in this ruling.
#7September 1, 2023· Wizards of the Coast
If an adventurer card ends up in exile for any other reason than by exiling itself while resolving, it won’t give you permission to cast it as a permanent spell.
No other card is named in this ruling.
#8September 1, 2023· Wizards of the Coast
You must still follow any timing restrictions and permissions for the permanent spell you cast from exile. Normally, you’ll be able to cast it only during your main phase while the stack is empty.
No other card is named in this ruling.
#9September 1, 2023· Wizards of the Coast
If an effect copies an Adventure spell, that copy is exiled as it resolves. It ceases to exist as a state-based action; it’s not possible to cast the copy as a permanent.
No other card is named in this ruling.
#10September 1, 2023· Wizards of the Coast
An effect may refer to a card, spell, or permanent that “has an Adventure.” This refers to a card, spell, or permanent that has an adventurer card’s set of alternative characteristics, even if they’re not being used and even if that card was never cast as an Adventure.
No other card is named in this ruling.
#11September 1, 2023· Wizards of the Coast
If an effect refers to a card, spell, or permanent that has an Adventure, it won’t find an instant or sorcery spell on the stack that’s been cast as an Adventure.
No other card is named in this ruling.
#12September 1, 2023· Wizards of the Coast
If an object becomes a copy of an object that has an Adventure, the copy also has an Adventure. If it changes zones, it will either cease to exist (if it’s a token) or cease to be a copy (if it’s a nontoken permanent), and so you won’t be able to cast it as an Adventure.
No other card is named in this ruling.
#13September 1, 2023· Wizards of the Coast
If an effect instructs you to choose a card name, you may choose the alternative Adventure name. Consider only the alternative characteristics to determine whether that is an appropriate name to choose.
No other card is named in this ruling.
#14September 1, 2023· Wizards of the Coast
Casting a card as an Adventure isn’t casting it for an alternative cost. Effects that allow you to cast a spell for an alternative cost or without paying its mana cost may allow you to apply those to the Adventure.
No other card is named in this ruling.