Karn, Silver Golem, Leyline of Abundance, and Basalt Monolith

Prerequisites

• Karn, Silver Golem on the battlefield
• Leyline of Abundance on the battlefield
• Basalt Monolith on the battlefield
• Basalt Monolith does not have summoning sickness
• available

Steps

1. Activate Karn by paying , causing Basalt Monolith to become an artifact creature until end of turn
2. Activate Basalt Monolith's first ability by tapping it, adding
3. Activate Basalt Monolith's last ability by paying , untapping it
4. Repeat from step 2

Results

• Infinite +1/+1 counters
• Infinite colorless mana
• Infinite green mana