Bristly Bill, Spine Sower, and Devoted Druid

Prerequisites

• Bristly Bill, Spine Sower on the battlefield
• Devoted Druid on the battlefield
• available

Steps

1. Activate Bristly Bill by paying , doubling the number of +1/+1 counters on each creature you control
2. Activate Devoted Druid's first ability by tapping it, adding
3. Activate Devoted Druid's second ability by putting a -1/-1 counter on it, untapping it
4. Repeat from step 2 four additional times
5. Repeat from step 1

Results

• Infinite green mana
• Infinite +1/+1 counters on creatures you control that have a +1/+1 counter on them