Cast Apex Altisaur by paying {7}{G}{G}.
When Apex Altisaur enters, its first ability triggers.
Holding priority, cast Rootborn Defenses by paying its mana cost, giving creatures you control indestructible until end of turn.
Resolve the Apex Altisaur trigger, causing it to fight a creature you don't control.
If the opposing creature dealt damage to Apex Altisaur, Apex Altisaur's second ability and Wrathful Raptors trigger.
Resolve the Wrathful Raptors trigger, dealing damage to any opponent.
Resolve the Apex Altisaur trigger, causing it to fight a creature you don't control.
Repeat from step 4 until your opponents control no creatures. If they happen to control an indestructible creature with power above 0, this loop can be done infinitely.

Destroy all creatures opponents control

Near-infinite damage

Apex Altisaur

Wrathful Raptors

Rootborn Defenses

Cast Rootborn Defenses by paying {2}{W}, giving creatures you control indestructible until end of turn.
Activate Krark-Clan Shaman by sacrificing an artifact, dealing 1 damage to each creature without flying.
Sonic's second ability triggers for each creature you control with haste or flash that was dealt damage, creating that many tapped Treasure tokens.
Repeat from step 2.

Infinite artifact ETB

Infinite artifact LTB

Infinite artifact sacrifice triggers

Infinite artifact tokens

Infinite tapped Treasure tokens

Infinite damage to creatures

Sonic the Hedgehog

Krark-Clan Shaman

Give Red Hulk and Boros Reckoner indestructible using Rootborn Defenses.
Deal damage to Red Hulk.
Red Hulk triggers, putting a +1/+1 counter on it and dealing damage to Boros Reckoner.
Boros Reckoner triggers, dealing damage to Red Hulk.
Repeat from step 3.

Infinite +1/+1 counters on a creature

Infinite damage to one opponent

Red Hulk

Boros Reckoner

Combos with "Rootborn Defenses"