Necrotic Ooze + Devoted Druid + Channeler Initiate

Necrotic Ooze

Devoted Druid

Channeler Initiate

How it works

1. Tap Necrotic Ooze using Devoted Druid's ability to add .
2. Untap Necrotic Ooze using Devoted Druid's ability, giving it a -1/-1 counter.
3. Tap Necrotic Ooze and remove a -1/-1 counter use Channeler Initiate's ability to add 1 of any color.
4. Repeat for infinite mana.