Retrofitter Foundry, Clock of Omens, and Stridehangar Automaton

Prerequisites

• Retrofitter Foundry on the battlefield
• Clock of Omens on the battlefield
• Stridehangar Automaton on the battlefield
• You control a Thopter

Steps

1. Activate Retrofitter Foundry's fourth ability by tapping it and sacrificing a Thopter, creating a 4/4 Construct and a 1/1 Thopter artifact creature token
2. Activate Clock of Omens by tapping the Construct and Thopter, untapping Retrofitter Foundry
3. Repeat

Results

• Infinite ETB
• Infinite tapped creature tokens