Vrondiss and Scourge of Valkas on the battlefield.
You have a way to give Vrondiss indestructible.
You have a way to deal damage to Vrondiss.
Steps
Give Vrondiss indestructible by any method.
Deal damage to Vrondiss.
Vrondiss triggers, creating a 5/4 Dragon Spirit creature token.
The Dragon Spirit enters the battlefield, triggering Scourge of Valkas, causing the Dragon Spirit to deal damage to Vrondiss equal to the number of Dragons you control.
The Dragon Spirit and Vrondiss trigger.
Resolve the Dragon Spirit trigger, causing you to sacrifice it.
Resolve the Vrondiss trigger, creating a 5/4 Dragon Spirit creature token.