Visions of Dread — ruling 1

If you leave the game while controlling permanents owned by other players that entered the battlefield under your control, those permanents are exiled. If the other players leave the game, they take their cards with them. (By contrast, if you leave the game while controlling permanents owned by another player you gained control of, those control-changing effects end and the permanents return to their previous controllers.)

Visions of Dread — ruling 2

If your commander is under the control of another player as you cast Visions of Dread using its flashback ability, that commander's mana value can be used to determine the value of X.

Visions of Dread — ruling 3

The cost-reduction effect that applies if you cast Visions of Dread using flashback applies only to the generic portion of the cost to cast it, although it can apply to any additional costs there may be to cast the spell. It can't reduce any colored mana required to cast the spell.

Visions of Dread — ruling 4

“Flashback [cost]” means “You may cast this card from your graveyard by paying [cost] rather than paying its mana cost” and “If the flashback cost was paid, exile this card instead of putting it anywhere else any time it would leave the stack.”

Visions of Dread — ruling 5

You must still follow any timing restrictions and permissions, including those based on the card's type. For instance, you can cast a sorcery using flashback only when you could normally cast a sorcery.

Visions of Dread — ruling 6

To determine the total cost of a spell, start with the mana cost or alternative cost (such as a flashback cost) you're paying, add any cost increases, then apply any cost reductions. The mana value of the spell is determined only by its mana cost, no matter what the total cost to cast the spell was.

Visions of Dread — ruling 7

A spell cast using flashback will always be exiled afterward, whether it resolves, is countered, or leaves the stack in some other way.

Visions of Dread — ruling 8

You can cast a spell using flashback even if it was somehow put into your graveyard without having been cast.

Visions of Dread : règles, fonctionnement et interactions (MTG)

Visions of Dread 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

Target opponent puts a creature card of their choice from their graveyard onto the battlefield under your control. Flashback . This spell costs less to cast this way, where X is the greatest mana value of a commander you own on the battlefield or in the command zone. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

How it works : Visions of Dread

Original English text — Wizards of the Coast / Scryfall

#1September 24, 2021· Wizards of the Coast
If you leave the game while controlling permanents owned by other players that entered the battlefield under your control, those permanents are exiled. If the other players leave the game, they take their cards with them. (By contrast, if you leave the game while controlling permanents owned by another player you gained control of, those control-changing effects end and the permanents return to their previous controllers.)
No other card is named in this ruling.
#2September 24, 2021· Wizards of the Coast
If your commander is under the control of another player as you cast Visions of Dread using its flashback ability, that commander's mana value can be used to determine the value of X.
No other card is named in this ruling.
#3September 24, 2021· Wizards of the Coast
The cost-reduction effect that applies if you cast Visions of Dread using flashback applies only to the generic portion of the cost to cast it, although it can apply to any additional costs there may be to cast the spell. It can't reduce any colored mana required to cast the spell.
No other card is named in this ruling.
#4September 24, 2021· Wizards of the Coast
“Flashback [cost]” means “You may cast this card from your graveyard by paying [cost] rather than paying its mana cost” and “If the flashback cost was paid, exile this card instead of putting it anywhere else any time it would leave the stack.”
No other card is named in this ruling.
#5September 24, 2021· Wizards of the Coast
You must still follow any timing restrictions and permissions, including those based on the card's type. For instance, you can cast a sorcery using flashback only when you could normally cast a sorcery.
No other card is named in this ruling.
#6September 24, 2021· Wizards of the Coast
To determine the total cost of a spell, start with the mana cost or alternative cost (such as a flashback cost) you're paying, add any cost increases, then apply any cost reductions. The mana value of the spell is determined only by its mana cost, no matter what the total cost to cast the spell was.
No other card is named in this ruling.
#7September 24, 2021· Wizards of the Coast
A spell cast using flashback will always be exiled afterward, whether it resolves, is countered, or leaves the stack in some other way.
No other card is named in this ruling.
#8September 24, 2021· Wizards of the Coast
You can cast a spell using flashback even if it was somehow put into your graveyard without having been cast.
No other card is named in this ruling.
#9September 24, 2021· Wizards of the Coast
If a card with flashback is put into your graveyard during your turn, you can cast it if it's legal to do so before any other player can take any actions.
No other card is named in this ruling.