Altar of Dementia + Horde of Notions + Intruder Alarm + Jegantha, the Wellspring

WUBRG identity

Commander legal

The 4 combo pieces

• Altar of Dementia
• Horde of Notions
• Intruder Alarm
• Jegantha, the Wellspring

What must be in place

Jegantha does not have summoning sickness.
You control another nontoken Elemental creature.

How to execute it

1. Activate Altar of Dementia by sacrificing any other nontoken Elemental creature, causing target player to mill cards equal to the sacrificed creature's power.
2. Activate Jegantha by tapping it, adding {W}{U}{B}{R}{G} that can't be spent to pay generic mana costs.
3. Activate Horde of Notions by paying {W}{U}{B}{R}{G}, casting any Elemental creature from your graveyard without paying its mana cost.
4. The Elemental enters the battlefield, triggering Intruder Alarm, untapping all creatures.
5. Repeat.

What the combo produces

• Infinite creature LTB
• Infinite death triggers
• Infinite ETB
• Infinite mana creatures you control can produce
• Infinite mill
• Infinite sacrifice triggers
• Infinite self-mill
• Infinite storm count
• Infinite untap of creatures