Intruder Alarm + Aethersnipe

Prerequisites

You control creatures that can tap to produce at least {2}{U}{U}.

Steps

1. Activate mana-producing creatures you control by tapping them, adding at least {2}{U}{U}.
2. Cast Aethersnipe for its evoke cost by paying {1}{U}{U}.
3. When Aethersnipe enters the battlefield, both of its abilities trigger and Intruder Alarm triggers; put the evoke trigger on the stack first.
4. Resolve the Intruder Alarm trigger, untapping all creatures.
5. Resolve Aethersnipe's first ability, returning it from the battlefield to your hand.
6. Resolve Aethersnipe's evoke trigger, failing to sacrifice it since it is not on the battlefield.
7. Repeat.