Thranduil, the Elvenking, Devoted Druid, and Immaculate Magistrate

Prerequisites

• Thranduil, the Elvenking on the battlefield
• Devoted Druid in the graveyard
• Immaculate Magistrate in the graveyard

Steps

1. Activate Thranduil using Immaculate Magistrate's ability by tapping it, putting a +1/+1 counter on Thranduil for each Elf you control
2. Activate Thranduil using Devoted Druid's second ability by putting a -1/-1 counter on it, untapping it
3. Repeat

Results

• Infinite +1/+1 counters on creatures you control
• Infinite green mana