This one of the better pieces I've seen on DA of a magic-user of any sort. He appears like a man given over to sorcery, not so some strange amalgamation of human form and absurd occult drama. Very well done.
The earlier piece definitely conveyed drama, but this one with its grimy skin, hard-edged tone, the attention to the thumbnail, greasy and patchy beard, the sneer, the travel-stained (and well textured) clothing, all make this summoner a very credible image.
I would encourage you to continue in this vein. Such art gives dignity to fantasy, allowing a very reasonable suspension of disbelief as the image conveys its own integral and believable reality. Too many artists are given over to useless chain-mail-bikinis, unwieldable eight-foot-bastard-swords, and wizards whose attire and accoutrement are fantastic to the point of being preposterous, inane, and simply unreasonable. I applaud your sensible technique.
That cloth is so... wet! Very well done man, painting cloth wet like that takes some serious skill. Also, that magenta tinge in the edges of the blue magical colums in the background makes this very cinematic... are they from a reference or did you paint the magenta by choice?