Thunderous Mutation in Steal an Egg
In the Stormheart Cave in Stormlands, trade 150 Sparks with Rumble at the Thunder Trade-In for one Thunderous Mutation. Put 3 Stormglass into the Storm Conductor to start a Storm Rush, then fly to collect Sparks.
Cost per consumable 150 SparksApplication chance UnconfirmedIncome multiplier ×2.75

A successful application gives a ×2.75 income multiplier. The application chance is still unconfirmed.
Skyfall and Storm Rush guide · How do mutations work in Steal an Egg?

