Marvin, Murderous Mimic + Pili-Pala + Arbor Adherent

Marvin, Murderous Mimic

Pili-Pala

Arbor Adherent

How it works

1. Activate Marvin using Arbor Adherent's ability by tapping it, adding four mana of any color.
2. Activate Marvin using Pili-Pala's ability by paying 2 and untapping it, adding one mana of any color.
3. Repeat.