For Alchemy the list of illustrators from
here is:
Antonio Catalán
Matthias Catrein
Jacob Corn
Julien Delval
Alex Drummond
Klemens Franz
Martin Hoffmann
Simon Jannerland
Ryan Laukat
Harald Lieske
Marcel-André Casasola Merkle
Kieron O'Gorman
Claus Stephan
Franz Vohwinkel
But Antonio Catalan is the only without a specific piece of art attached to a card, so I would guess he is the artist for the cover?