Activate Bloom Tender by tapping it, adding three mana of each color.
Activate Legacy Weapon by paying {W}{U}{B}{R}{G}, exiling Eternal Scourge.
Cast Eternal Scourge from exile by paying {3}.
When Eternal Scourge enters the battlefield, Intruder Alarm triggers, untapping all creatures.
Repeat.

Infinite LTB

Infinite ETB

Infinite colored mana

Infinite storm count

Infinite untap of creatures

Infinite mana creatures you control can produce

Exile all permanents opponents control

Mass Land Denial

Infinite untap of creatures you control

Legacy Weapon

Bloom Tender

Nyxbloom Ancient

Intruder Alarm

Eternal Scourge

Activate Faeburrow Elder by tapping it, adding three mana of each color.
Activate Legacy Weapon by paying {W}{U}{B}{R}{G}, exiling Eternal Scourge.
Cast Eternal Scourge from exile by paying {3}.
When Eternal Scourge enters the battlefield, Intruder Alarm triggers, untapping all creatures.
Repeat.

Faeburrow Elder

Activate Faeburrow Elder by tapping it, adding {W}{W}{U}{U}{B}{B}{R}{R}{G}{G}.
Activate Legacy Weapon by paying {W}{U}{B}{R}{G}, exiling Eternal Scourge.
Cast Eternal Scourge from exile by paying {3}.
When Eternal Scourge enters the battlefield, Intruder Alarm triggers, untapping all creatures.
Repeat.

Mana Reflection

Activate Bloom Tender by tapping it, adding {W}{W}{U}{U}{B}{B}{R}{R}{G}{G}.
Activate Legacy Weapon by paying {W}{U}{B}{R}{G}, exiling Eternal Scourge.
Cast Eternal Scourge from exile by paying {3}.
When Eternal Scourge enters the battlefield, Intruder Alarm triggers, untapping all creatures.
Repeat.

Combos with "Legacy Weapon"