Needs must when the devil drives, as the saying goes. It’s not quite apt here but it sure sounds good. There was a need though, and here is the result. If a group finds itself in Guistenal, are captured by dray, are human, and fail to escape, it’s very likely that they will be forced into undergoing dray transformation.
When a PC not indigenous to Guistenal or New Guistenal undergoes the dray transformation in Dungeon World, a compendium class is ideal (and I daresay necessary). Certainly, there might be a dray race one might incorporate into the already established classes but that would infer (using 2e thinking) that the character is from New Guistenal. A dray racial option might be the way to go if, as in for 4e, dray were prevalent throughout the tablelands, but the campaign and players would drive that decision. It so happens in this case, it’s a 2e-like environment.
From the 2e City by the Silt Sea supplement there wasn’t much more to the dray than being tougher than other races. Certainly they looked terrifying and were more fierce, and so they should be for Dregoth’s use of them in his “Day of Light.” In order to convey the 2e dray best I borrowed from Androc and gnome7’s Juggernaut and the bardic lore move.
Dark Sun Dungeon World Dray Compendium Class (pdf)
Dark Sun Dungeon World Dray Compendium Class (docx)
The art above is from William Samir Muniz and has a rather nice oil painting portrait style. Here’s another in that same style.