You can avoid the forced of Smaug the Magnificent by Rider of the Mark hability?
The text of the ally is: Response: After Rider of the Mark changes control, discard a shadow card dealt to an enemy you are engaged with.
And the text of Smaug: If Smaug the Magnificent is dealt a shadow card with a burgle effect, he makes an additional attack immediately after this one.
Smaug is immune to player cards effects. Is immune also to the text of Rider of the Mark?
PD: one question: which enemy is his shadow card discarded, the enemy of new controler or the old controler?