Hello back and welcome to the forum. Monster Mud is used to thicken/bulk up items. Usually cloth is dipped into it and then it can be draped on whatever you need and when it dries it looks like it was carved out of stone. Monster mud is made by mixing joint compound with latex paint.
Drylok is a masonry (basement) waterproofing paint and it used to waterproof items. I also use it to paint tombstones gray and the grit in the paint gives it a stone-like texture. Hope that helps.