Knacksaw Clique, Grand Architect, Training Grounds, and Signpost Scarecrow

Prerequisites

• Knacksaw Clique on the battlefield
• Grand Architect on the battlefield
• Training Grounds on the battlefield
• Signpost Scarecrow on the battlefield

Steps

1. Activate Grand Architect's second ability by tapping Knacksaw Clique, adding that can only be spent to cast artifact spells or to activate abilities of artifacts
2. Activate Signpost Scarecrow by paying , adding
3. Activate Knacksaw Clique by paying and untapping it, exiling the top card of an opponents library and allowing you to cast it this turn
4. Repeat

Results

• Cast all cards from your opponents' libraries
• Exile each opponent's library
• Infinite colored mana
• Infinite colorless mana that can only be spent to activate abilities of artifacts
• Infinite colorless mana that can only be spent to cast artifact spells