When Bladewing's Thrall enters, Dragonback Assault triggers, as Bladewing's Thrall is a land due to Ashaya.
Holding priority, activate Overgrown Estate by sacrificing Bladewing's Thrall.
Resolve the Dragonback Assault trigger, creating a 4/4 Dragon creature token.
When the Dragon enters, Bladewing's Thrall triggers, returning itself from your graveyard to the battlefield.
Repeat from step 2.
This clever loop relies on Ashaya, Soul of the Wild to fundamentally rewrite the rules of the battlefield, turning Bladewing's Thrall—and every other nontoken creature you control—into a Forest land. Because of this land-type shift, whenever Bladewing's Thrall enters the battlefield, Dragonback Assault sees a land entering and triggers its damage ability, while Overgrown Estate provides the safe outlet to sacrifice the Thrall in response. That sacrifice drops Bladewing's Thrall into the graveyard, but the resulting Dragonback Assault token generation immediately coaxes the Thrall right back out of the graveyard by its own recursive trigger, setting up an endless cycle of sacrifice, lifegain, and dragon-fueld rebirth.