A player controls a nontoken creature with toughness equal to one.
Steps
Activate Soul Collector by tapping it, dealing 1 damage to any nontoken creature with toughness equal to one.
The creature dies as a state-based action due to having zero toughness, triggering Soul Collector, returning the creature from a graveyard onto the battlefield under your control.
The creature enters the battlefield, triggering Intruder Alarm, untapping all creatures.