Artist Robert Bliss is a particularly good choice for a Halloween Sketches, since he contributed such creepy work such as Skulking Ghost, Reanimate and Cannibalize back in the Mirage and Tempest block days. Even Robert's famous Mirage version of Pacifism features a zombie! He returns to Magic illustration with Ravnica.
The first step of the creation of a card's art is its art description. The art description tells the artist what the card will do, what its flavor is, and what the mood of the illustration should be. Here were the instructions given to Robert for Keening Banshee:
Color: Black (non-guild)
Location: Night sky
Action: Show a banshee, the ghost of a young woman who died prematurely, floating through a moonlit sky. The banshee is screaming, and the scream is enough to drive anyone mad.
Focus: The banshee
Mood: Beautiful and madness-inducing
The next step is for the artist to submit sketches of his or her vision of the art description.
Here is Robert's first concept sketch submitted for Keening Banshee.
This sketch shows the ghoulish scream the art team was looking for, and the trademark Bliss macabre-creature feel. It also captures the moonlit sky in the art description, but the sense of a flying spirit is lost here -- there's no feel that the banshee is airborne without more context.
A terrific improvement -- here we see clearly that the banshee is flying, by the trees going by beneath her. And we see that she's a spirit by the eerie curls that form at the ends of her legs and clothing. However, there's a setting problem here -- can you spot it?
It's the trees! Ravnica is an unbroken urban sprawl -- there are no areas of forest as seen in that second sketch. Robert submitted this final art, replacing the trees with the rooftops of buildings.
And here's the card in its final state, as you can see in booster packs of Ravnica: City of Guilds. Creep out your opponent (with a little help from Robert Bliss) with Keening Banshee!