Batman and Mayor McCaskill minifigures are included, along with a small clay trap to ensnare a minifig of your choice. (This, of course, can also be disassembled if you want more little brown bits to add on to your Clayface.) McCaskill goes well with the GCPD minifigs in a display, and be aware that the small mark on her face isn't a defect, but a "beauty mark" that is supposed to be there. Aside from some slightly different facial expressions, Batman is no different than the numerous other Batman minifigs you already have if you've been buying the TLBM sets. It's a damn good minifg, and I like having some extras to pop into various displays, so I definitely don't mind getting another. Plus, you can hardly fault TLg for including Batman minifigs in their Batman sets!
Clayface Splat Attack is easily one of my favorite sets from the TLBM series to date, a standout in a fantastic lineup. Recommended.