Halo Fountain, Karn, Silver Golem, and Prismatic Geoscope

Prerequisites

• Halo Fountain on the battlefield
• Karn, Silver Golem on the battlefield
• Prismatic Geoscope on the battlefield
• available

Steps

1. Activate Karn twice by paying , causing Halo Fountain and Prismatic Geoscope to become a creature
2. Activate Prismatic Geoscope by tapping it, adding at least
3. Activate Halo Fountain's second ability by paying , tapping it, and then untapping it and Prismatic Geoscope, causing you to draw a card
4. Repeat from step 2

Results

• Infinite card draw
• Near-infinite ETB
• Infinite draw triggers
• Near-infinite colored mana
• Near-infinite creature tokens
• Near-infinite untap of creatures you control
• Near-infinite mana creatures you control can produce