Iroas, God of Victory — ruling 1

If an effect causes a God to lose all abilities, its ability that causes it to stop being a creature still applies if appropriate.

Iroas, God of Victory — ruling 2

Your devotion to two colors is the number of mana symbols among mana costs of permanents you control that are the first color, the second, or both. If an effect counts your devotion to two colors, a hybrid symbol that is both of those colors is counted just once.

Iroas, God of Victory — ruling 3

The type-changing ability that can make a God not be a creature functions only on the battlefield. It's always a creature card in other zones, regardless of your devotion to its color. It's always a creature spell while it's on the stack.

Iroas, God of Victory — ruling 4

As a God enters the battlefield, your devotion to its color will determine whether any replacement effects that affect creatures entering the battlefield apply to that God. Because replacement effects are considered before the God is on the battlefield, the mana symbols in its mana cost won't be counted when determining this.

Iroas, God of Victory — ruling 5

When a God enters the battlefield, your devotion to its color (including the mana symbols in the mana cost of the God itself) will determine if a creature entered the battlefield or not for abilities that trigger whenever a creature enters the battlefield.

Iroas, God of Victory — ruling 6

If a God stops being a creature, it loses the type creature and the creature type God. It continues to be a legendary enchantment.

Iroas, God of Victory — ruling 7

The abilities of Gods function as long as they're on the battlefield, regardless of whether they're creatures.

Iroas, God of Victory — ruling 8

If a God is attacking or blocking and it stops being a creature, it will be removed from combat. It won't rejoin combat if it resumes being a creature later during that combat.

Iroas, God of Victory : règles, fonctionnement et interactions (MTG)

Iroas, God of Victory 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

Indestructible As long as your devotion to red and white is less than seven, Iroas isn't a creature. Creatures you control have menace. Prevent all damage that would be dealt to attacking creatures you control.

How it works : Iroas, God of Victory

Original English text — Wizards of the Coast / Scryfall

#1January 24, 2020· Wizards of the Coast
If an effect causes a God to lose all abilities, its ability that causes it to stop being a creature still applies if appropriate.
No other card is named in this ruling.
#2January 24, 2020· Wizards of the Coast
Your devotion to two colors is the number of mana symbols among mana costs of permanents you control that are the first color, the second, or both. If an effect counts your devotion to two colors, a hybrid symbol that is both of those colors is counted just once.
No other card is named in this ruling.
#3January 24, 2020· Wizards of the Coast
The type-changing ability that can make a God not be a creature functions only on the battlefield. It's always a creature card in other zones, regardless of your devotion to its color. It's always a creature spell while it's on the stack.
No other card is named in this ruling.
#4January 24, 2020· Wizards of the Coast
As a God enters the battlefield, your devotion to its color will determine whether any replacement effects that affect creatures entering the battlefield apply to that God. Because replacement effects are considered before the God is on the battlefield, the mana symbols in its mana cost won't be counted when determining this.
No other card is named in this ruling.
#5January 24, 2020· Wizards of the Coast
When a God enters the battlefield, your devotion to its color (including the mana symbols in the mana cost of the God itself) will determine if a creature entered the battlefield or not for abilities that trigger whenever a creature enters the battlefield.
No other card is named in this ruling.
#6January 24, 2020· Wizards of the Coast
If a God stops being a creature, it loses the type creature and the creature type God. It continues to be a legendary enchantment.
No other card is named in this ruling.
#7January 24, 2020· Wizards of the Coast
The abilities of Gods function as long as they're on the battlefield, regardless of whether they're creatures.
No other card is named in this ruling.
#8January 24, 2020· Wizards of the Coast
If a God is attacking or blocking and it stops being a creature, it will be removed from combat. It won't rejoin combat if it resumes being a creature later during that combat.
No other card is named in this ruling.
#9January 24, 2020· Wizards of the Coast
Counters put on a God remain on it while it's not a creature, even if they have no effect.
No other card is named in this ruling.
#10April 26, 2014· Wizards of the Coast
Iroas's last ability prevents all damage dealt to attacking creatures you control, not just combat damage.
No other card is named in this ruling.