Draconian, Slayer of the Skies

Flying
First Strike
Devoid (This creature has no colour)
This spell cannot be countered
When Draconian, Slayer of the Skies enters the battlefield, destroy all coloured permanents
(Regardless of whether or not they have Indestructible).Exile Draconian, Slayer of the Skies at the beginning of your next 3rd next end step.