Berta, Wise Extrapolator + Agatha's Soul Cauldron + Farmstead Gleaner + Phantom Nantuko

Prerequisites

• There is at least one +1/+1 counter on Berta.
• Berta does not have summoning sickness.

Steps

1. 1Activate Berta using Phantom Nantuko's ability by tapping them, putting a +1/+1 counter on Berta.
2. 2Berta's second ability triggers, adding one mana of any color.
3. 3Activate Berta using Farmstead Gleaner's ability by paying and untapping them, putting a +1/+1 counter on Berta.
4. 4Berta's second ability triggers, adding one mana of any color.
5. 5Repeat.

Effects

• Infinite +1/+1 counters on a creature