Bug of Collection

I have bought a lot of packs of ‘Descent of Dragon’ I have found some common cards of the set, in triple copy too, but some of them I have never found.
I think there is a bug.

Are you sure they’re from Descent? Mind sharing a screenshot?

In the mage class, for example, I have 3 copies of Violet Spellwing, but no one of Arcane Amplifier
I have never received 13 common cards from this set.

Sorry buy I can’t share the photo, how can I do it?

Arcane Amplifier is not opened from packs. You get two copies by defeating Dragoncaster Askaara in Galakrond’s Awakening’s Chapter 2 of E.V.I.L. campaign.

See here: How to share links to screenshots, videos, and replays