# Thunderous Mutation in Steal an Egg | STEAL EGG

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[STEAL EGG](/en/)/[Mutation guide](/en/guides/mutations-guide/)Update 13

# 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![Thunderous Mutation crystal with white lightning, blue rings and clouds.](/assets/images/mutations/thunderous.webp)

A successful application gives a ×2.75 income multiplier. The application chance is still unconfirmed.

[Skyfall and Storm Rush guide](/en/guides/stormlands-skyfall-guide/#thunderous) · [How do mutations work in Steal an Egg?](/en/guides/egg-mutation-income-calculator/)[![Thunder Trade-In panel showing the exchange of 150 Sparks for 1 Thunderous Mutation.](/assets/images/stormlands-update-13/thunder-trade-in-150-sparks.webp)](/assets/images/stormlands-update-13/thunder-trade-in-150-sparks.webp)Thunder Trade-In panel showing the exchange of 150 Sparks for 1 Thunderous Mutation.