Necrotic Ooze + Boa Constrictor + Devoted Druid

Necrotic Ooze

Boa Constrictor

Devoted Druid

How it works

1. Activate Necrotic Ooze using Boa Constrictor's ability by tapping it, giving it +3/+3 until end of turn.
2. Activate Necrotic Ooze using Devoted Druid's second ability by putting a -1/-1 counter on it, untapping it.
3. Repeat.
4. Once Necrotic Ooze has infinite toughness, you may instead use Devoted Druid's first ability to get infinite green mana.

Necrotic Ooze serves as the magical vessel for this entire sequence, inheriting every activated ability from the creature cards resting in your graveyard. By feeding it the untap ability of Devoted Druid, you can tap and untap the Ooze ad infinitum, layering on -1/-1 counters that would normally spell doom for a fragile creature. However, because Boa Constrictor's pump ability is also sitting in the graveyard granting a +3/+3 bonus, you can offset those shrinking counters entirely, pumping the Ooze's toughness safely into the stratosphere. Once your monstrous Ooze is bolstered by that massive toughness cushion, you can finally tap it for green mana using Devoted Druid's other ability to generate an endless supply of green mana.