Mythos of Vadrok — ruling 1

Each chosen target must receive at least 1 damage.

Mythos of Vadrok — ruling 2

If some of the targets become illegal for Mythos of Vadrok, the original division of damage still applies, but the damage that would have been dealt to illegal targets isn’t dealt at all.

Mythos of Vadrok — ruling 3

Activated abilities contain a colon. They’re generally written “[Cost]: [Effect].” Some keyword abilities are activated abilities and will have colons in their reminder text. Triggered abilities (starting with “when,” “whenever,” or “at”) are unaffected by Mythos of Vadrok.

Mythos of Vadrok — ruling 4

The target creatures and planeswalkers will be unable to attack, block, or have their abilities activated even if the damage that would be dealt to them is prevented. However, if one of those permanents becomes an illegal target, it will be able to attack, block, and have its abilities activated.

Mythos of Vadrok — ruling 5

The abilities of the Mythos check what colors of mana were spent to cast the spell. It’s not an alternative cost to cast the spell.

Mythos of Vadrok — ruling 6

If an effect copies the Mythos spell, no mana was spent to cast the copy, so the copy won’t receive the bonus.

Mythos of Vadrok — ruling 7

The ability checks what mana was actually spent to cast a spell. If an effect allows you to spend mana “as though it were mana” of any color or type, that allows you to spend mana you couldn’t otherwise spend, but it doesn’t change what mana you spent to cast the spell.

Mythos of Vadrok — ruling 8

If an effect allows you to cast a spell without paying its mana cost, you can’t choose to cast it and pay unless another rule or effect allows you to cast that spell for a cost. Similarly, you can’t waive a cost reduction unless that effect says you may.

Mythos of Vadrok : règles, fonctionnement et interactions (MTG)

Mythos of Vadrok 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

Mythos of Vadrok deals 5 damage divided as you choose among any number of target creatures and/or planeswalkers. If was spent to cast this spell, until your next turn, those permanents can't attack or block and their activated abilities can't be activated.

How it works : Mythos of Vadrok

Original English text — Wizards of the Coast / Scryfall

#1April 17, 2020· Wizards of the Coast
Each chosen target must receive at least 1 damage.
No other card is named in this ruling.
#2April 17, 2020· Wizards of the Coast
If some of the targets become illegal for Mythos of Vadrok, the original division of damage still applies, but the damage that would have been dealt to illegal targets isn’t dealt at all.
No other card is named in this ruling.
#3April 17, 2020· Wizards of the Coast
Activated abilities contain a colon. They’re generally written “[Cost]: [Effect].” Some keyword abilities are activated abilities and will have colons in their reminder text. Triggered abilities (starting with “when,” “whenever,” or “at”) are unaffected by Mythos of Vadrok.
No other card is named in this ruling.
#4April 17, 2020· Wizards of the Coast
The target creatures and planeswalkers will be unable to attack, block, or have their abilities activated even if the damage that would be dealt to them is prevented. However, if one of those permanents becomes an illegal target, it will be able to attack, block, and have its abilities activated.
No other card is named in this ruling.
#5April 17, 2020· Wizards of the Coast
The abilities of the Mythos check what colors of mana were spent to cast the spell. It’s not an alternative cost to cast the spell.
No other card is named in this ruling.
#6April 17, 2020· Wizards of the Coast
If an effect copies the Mythos spell, no mana was spent to cast the copy, so the copy won’t receive the bonus.
No other card is named in this ruling.
#7April 17, 2020· Wizards of the Coast
The ability checks what mana was actually spent to cast a spell. If an effect allows you to spend mana “as though it were mana” of any color or type, that allows you to spend mana you couldn’t otherwise spend, but it doesn’t change what mana you spent to cast the spell.
No other card is named in this ruling.
#8April 17, 2020· Wizards of the Coast
If an effect allows you to cast a spell without paying its mana cost, you can’t choose to cast it and pay unless another rule or effect allows you to cast that spell for a cost. Similarly, you can’t waive a cost reduction unless that effect says you may.
No other card is named in this ruling.