Splinter Twin, Devoted Druid, and Cathars' Crusade

Prerequisites

• Splinter Twin on the battlefield
• Devoted Druid on the battlefield
• Cathars' Crusade on the battlefield
• Splinter Twin attached to Devoted Druid
• Devoted Druid does not have summoning sickness

Steps

1. Activate Devoted Druid by tapping it, creating a token copy of it with haste
2. When the Devoted Druid token enters the battlefield, Cathars' Crusade triggers, putting a +1/+1 counter on each creature you control
3. Activate the nontoken Devoted Druid's second ability by putting a -1/-1 counter on it, untapping it
4. Repeat
5. Once you have infinite Devoted Druid tokens, you may tap them to get infinite

Results

• Infinite creature tokens with haste
• Infinite ETB
• Infinite green mana
• Infinite +1/+1 counters