Cybernetica Datasmith and Intruder Alarm on the battlefield.
Cybernetica Datasmith does not have summoning sickness.
You control a creature that can tap to add ({U} magic symbol) .
Steps
Activate a creature you control by tapping it, adding ({U} magic symbol) .
Activate Cybernetica Datasmith by paying ({U} magic symbol) and tapping it, causing a player to draw a card and another player to create a 4/4 Robot creature token.
The Robot enters the battlefield, triggering Intruder Alarm, untapping all creatures.
Repeat.
Results
Infinite card draw for any number of players.
Infinite creature tokens for any number of players.