Hellkite Charger + Shriekwood Devourer

Prerequisites

• You control up to seven lands that can tap to produce at least .
• You control a creature with power 7 or greater that does not have summoning sickness, and that cannot be blocked and killed by an opponent.

Steps

1. 1Declare any creature with power 7 or greater that cannot be blocked and killed by an opponent and Hellkite Charger if it isn't the aforementioned creature as attackers.
2. 2Shriekwood Devourer and Hellkite Charger trigger.
3. 3Resolve the Shriekwood Devourer trigger, untapping at least seven lands.
4. 4Holding priority, activate up to seven lands by tapping them, adding at least .
5. 5Resolve the Hellkite Charger trigger, causing you to pay to untap all attacking creatures you control and causing you to get an additional combat phase after this one.
6. 6Repeat.

Effects

• Infinite combat phases
• Infinite ETB
• Infinite mana lands you control can produce
• Infinite untap of lands you control