Activate Rex using Steelswarm Operator's second ability by tapping it, adding {U}{U} that can only be spent to activate abilities of artifact sources.
Activate Rex using Knacksaw Clique's ability by paying {1}{U} and untapping it, exiling the top card of an opponent's library with the ability to play that card this turn.
Repeat.

Exile each opponent's library

Rex, Cyber-Hound

Knacksaw Clique

Steelswarm Operator

Activate Steelswarm Operator's second ability by tapping it, adding {U}{U} that can only be spent to activate abilities of artifacts.
Activate Memnarch by paying {1}{U}{U}, causing Freed from the Real to become an artifact.
Activate Freed from the Real by paying {U}, untapping Steelswarm Operator.
Activate Steelswarm Operator's second ability by tapping it, adding {U}{U} that can only be spent to activate abilities of artifacts.
Repeat from step 3.

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

Memnarch

Freed from the Real

Activate Steelswarm Operator's second ability by tapping it, adding {U}{U} that can only be spent to activate abilities of artifacts.
Activate Filigree Sages by paying {U}, untapping Steelswarm Operator.
Repeat.

Infinite mana artifacts you control can produce

Infinite untap of artifacts you control

Filigree Sages

Training Grounds

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

Combos with "Steelswarm Operator"