Elvish Archdruid, and Umbral Mantle

Prerequisites

• Elvish Archdruid on the battlefield
• Umbral Mantle on the battlefield
• Umbral Mantle attached to Elvish Archdruid
• You control at least four Elves
• Elvish Archdruid does not have summoning sickness

Steps

1. Activate Elvish Archdruid by tapping it, adding at least
2. Activate Elvish Archdruid by paying and untapping it, giving itself +2/+2 until end of turn
3. Repeat

Results

• Infinitely large Elvish Archdruid until end of turn
• Infinite green mana