Ramses, Assassin Lord — ruling 1

As long as that player was attacked this turn by an Assassin you controlled, Ramses, Assassin Lord’s last ability triggers when that player loses the game for any reason, not just due to combat damage. This is true even if the Assassin is no longer on the battlefield, no longer under your control, or no longer an Assassin at the time that player loses the game.

Ramses, Assassin Lord — ruling 2

If you attack an opponent with a non-Assassin creature and that creature becomes an Assassin after attackers were declared, that player was not “attacked” this turn by an Assassin you controlled.

Ramses, Assassin Lord — ruling 3

Similarly, if an Assassin enters the battlefield under your control attacking a player, that creature didn’t “attack” and won’t cause this ability to trigger.

Ramses, Assassin Lord — ruling 4

For the last ability to trigger, an Assassin you controlled must have attacked the player. Attacking a planeswalker the player controls won’t count.

Ramses, Assassin Lord : règles, fonctionnement et interactions (MTG)

Ramses, Assassin Lord 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

Deathtouch Other Assassins you control get +1/+1. Whenever a player loses the game, if they were attacked this turn by an Assassin you controlled, you win the game.

How it works : Ramses, Assassin Lord

Original English text — Wizards of the Coast / Scryfall

#1September 9, 2022· Wizards of the Coast
As long as that player was attacked this turn by an Assassin you controlled, Ramses, Assassin Lord’s last ability triggers when that player loses the game for any reason, not just due to combat damage. This is true even if the Assassin is no longer on the battlefield, no longer under your control, or no longer an Assassin at the time that player loses the game.
No other card is named in this ruling.
#2September 9, 2022· Wizards of the Coast
If you attack an opponent with a non-Assassin creature and that creature becomes an Assassin after attackers were declared, that player was not “attacked” this turn by an Assassin you controlled.
No other card is named in this ruling.
#3September 9, 2022· Wizards of the Coast
Similarly, if an Assassin enters the battlefield under your control attacking a player, that creature didn’t “attack” and won’t cause this ability to trigger.
No other card is named in this ruling.
#4September 9, 2022· Wizards of the Coast
For the last ability to trigger, an Assassin you controlled must have attacked the player. Attacking a planeswalker the player controls won’t count.
No other card is named in this ruling.