Elemental Mastery, Nurturing Presence, and Devoted Druid

Prerequisites

• Elemental Mastery on the battlefield
• Nurturing Presence on the battlefield
• Devoted Druid on the battlefield
• Elemental Mastery and Nurturing Presence attached to Devoted Druid
• Devoted Druid does not have summoning sickness, and has a power of one or greater

Steps

1. Activate Devoted Druid by tapping it, creating at least one 1/1 Elemental creature token with haste
2. When the Elemental token(s) enter the battlefield, Devoted Druid triggers that many times, giving it +1/+1 until end of turn for each creature that entered the battlefield
3. Activate Devoted Druid by putting a -1/-1 counter on it, untapping it
4. Repeat
5. If Devoted Druid has a power of two or greater, Devoted Druid becomes infinitely large until end of turn, which allows you to use its mana ability instead to get infinite

Results

• Infinite creature tokens with haste
• Infinite ETB
• Infinite green mana
• Infinitely large Devoted Druid until end of turn