Royal assassin

[Subiskier]

If my opponent announces an attacker can I kill it with {royal assassin}? Does the attacker tap immediately?

[Keyeto]

Tapping the creature is part of the process for declaring an attacker, so yes. Once their creature is declared as an attacking creature, it will be tapped.

[Subiskier]

{royal assassin} is too good

[Jlamb5]

Tapping the creature is part of the process for declaring an attacker, so yes. Once their creature is declared as an attacking creature, it will be tapped.

Unless that creature has vigilance, right?

[scarsabrex]

Correct