I drew/painted it in Pixelmator, which is basically an inexpensive off-brand Photoshop for people who use outdated potato Macs like me.
I don't know exactly how much time I spent on it, but I
do know the precise date I started- June 26 of last year. I know this because I spent an unfortunate amount of time trying to reproduce Terrence's armor based off of Oz's description, only to have said armor destroyed by a club-wielding maniac in
an update on the same day. In terms of hours, the most specific answer I can give you is "many."
I'm not really sure what you mean when you say "involved brushwork." I have very little painting experience, so I didn't use special brush strokes or anything like that. I did make use of several quick custom brushes, though. All of those identical purpley flower things were made with one brush, with the hue and brightness set to vary a little bit. Same goes for the leaves on all of the bushes. Texturing Terrance's skin and the moss on the rocks involved layering multiple brushes to great an "organic" look.
I did use some cheaty tricks. The base grass layer is the most egregious example- I basically created a tiny patch of reasonably acceptable terrain using a combination of a dark spiky brush and a brighter spattery brush, then duplicated that little patch a bunch, and distorted and rotated the pieces to create something resembling a landscape. It's not so noticeable in the final image, but that's only because I compensating for my lazy editing by throwing in some scenery, some fog, and the aforementioned purplish flower thingies.
Outlining the little bumps on Terrance's armor was a pain, so I made generous use of the clone stamp to cut down on tedium. I used seperate layers with various blending effects to achieve the actual colors and values of the scales, the uppermost of which creates the irredescent effect in the final image. The structure and organization of these layers, by the way, is enough to make a graphic designer cry.
I also abused the burn and dodge tools quite a bit to correct some early shading mistakes on the bowl.
I made light use of a couple of filters at various points- in particular, a guassian blur, and Pixelmator's "motion effect," which creates an effect similar to Photoshop's fiber effect.