Halo Fountain, Vedalken Engineer, and Karn, Silver Golem

Prerequisites

• Halo Fountain on the battlefield
• Vedalken Engineer on the battlefield
• Karn, Silver Golem on the battlefield
• Vedalken Engineer and Halo Fountain do not have summoning sickness
• available

Steps

1. Activate Karn by paying , causing Halo Fountain to become an artifact creature until end of turn
2. Activate Vedalken Engineer by tapping it, adding that can only be spent to cast artifact spells or activate abilities of artifacts
3. Activate Halo Fountain's second ability by paying , tapping it and untapping Halo Fountain and Vedalken Engineer, causing you to draw a card
4. Repeat from step 2

Results

• Infinite card draw
• Infinite draw triggers