Halo Fountain, Incubation Druid, and Karn, Silver Golem

Prerequisites

• Halo Fountain on the battlefield
• Incubation Druid on the battlefield
• Karn, Silver Golem on the battlefield
• Halo Fountain and Incubation Druid do not have summoning sickness
• Incubation Druid has at least one +1/+1 counter on it
• available

Steps

1. Activate Karn by paying , causing Halo Fountain to become an artifact creature until end of turn
2. Activate Incubation Druid's first ability by tapping it, adding
3. Activate Halo Fountain's second ability by paying , tapping it and untapping it and Incubation Druid, causing you to draw a card
4. Repeat from step 2

Results

• Infinite card draw
• 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