At least one creature you control does not have summoning sickness.
NOTE: This combo can only persist as long as a creature card is milled with each iteration; as such, the more creatures you can tap, the lower your chances of failure.
Steps
Activate all creatures you control by tapping them.
Resolve the first creature's ability, causing target opponent to mill cards equal to the creature's toughness.
For each creature card milled this way,
Undead Alchemist triggers, exiling that card and causing you to create a 2/2 Zombie creature token.
If a Zombie is created, it enters the battlefield, triggering
Intruder Alarm, untapping all creatures.
Repeat from step 2 for each remaining trigger.
Repeat from step 1.
Results
Infinite mill.
Near-infinite creature tokens.
Near-infinite creature ETB.
Near-infinite untap of all creatures.
Metadata
Bracket tag
ExhibitionBracket 1+
For any deck
1
2
3
4
5
1 · Exhibition5 · cEDH
Bracket tags are estimated from the cards and results of each combo, as a guideline rather than a strict classification.