Unknown Artist
From Archon Arcana - The KeyForge Wiki
Some cards do not have an artist attributed, instead crediting the card to "Unknown Artist". Unfortunately, in the acquisition of the art assets from Fantasy Flight Games, some of the credits for the artwork used was lost.
Ghost Galaxy has advised that if the artist can be identified in the future, they will update the cards in the future print runs (as well as on the Master Vault.) Corrections can be sent to Ghost Galaxy via their contact page.