Breath of Fury and Living Hive on the battlefield.
Breath of Fury attached to another creature you control.
An opponent cannot block creatures you control.
You control a Mountain.
Steps
Deal combat damage to an opponent using Living Hive and the creature with Breath of Fury attached.
Breath of Fury and Living Hive trigger.
Resolve the Living Hive trigger, creating six 1/1 Insect creature tokens.
Resolve the Breath of Fury trigger, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to an Insect token, untap all creatures you control and get an additional combat phase after this one.