Agatha's Soul Cauldron + Horseshoe Crab + Steelswarm Operator

U identity

Commander legal

The 3 combo pieces

• Agatha's Soul Cauldron
• Horseshoe Crab
• Steelswarm Operator

How to execute it

1. Activate Steelswarm Operator's second ability by tapping it, adding {U}{U} that can only be spent to activate abilities of artifacts.
2. Activate Steelswarm Operator using Horseshoe Crab's ability by paying {U}, untapping it.
3. Repeat.

What the combo produces

• Infinite blue mana that can only be spent to activate abilities of artifacts
• Infinite blue mana that can only be spent to cast artifact spells