Necrotic Ooze, Auriok Bladewarden, and Devoted Druid

Prerequisites

• Necrotic Ooze on the battlefield
• Auriok Bladewarden in the graveyard
• Devoted Druid in the graveyard
• Necrotic Ooze does not have summoning sickness

Steps

1. Activate Necrotic Ooze using Auriok Bladewarden's ability by tapping it, giving it +X/+X until end of turn, where X is its power
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

Results

• Infinite green mana
• Infinitely large Necrotic Ooze until end of turn