Intruder Alarm

Enchantment, 2U (3)
Creatures don't untap during their controllers' untap steps.
Whenever a creature enters the battlefield, untap all creatures.¹
One footstep among many is silent. One footstep alone is deafening.
Illus. Luca Zontini

Gatherer Card Rulings [Nov 2009]

• 10/4/2004: If multiple creatures enter the battlefield at one time, this ability triggers once for each creature. This doesn't matter much, but it can in some cases.

Format Legality	Legal in Vintage, Legacy Banned in Extended, Standard
Printings (2/12)	Core Set - Eighth Edition (Rare) Stronghold (Rare)