A cream-based, water-proof, professional-grade cream foundation and/or concealer. I have had success with Dermablend, Bobbi brown, and Graftobian. Don’t put it on in one thick layer. Use a light touch. Use a brush or beauty blender. If you need to, add a second or third thin layer after it dries.
Always set with something like Ben Nye neutral set powder. Then set it with something like Ben Nye final seal setting spray. You will have much more success with this than just liquid foundation. If any of the scarring is reddish, get a green creme color corrector to rub on over it.