The Ghoul is cool, but there are some things that need attention in my opinion:
Firstly and most notably, when you have license 2 kobold, Ghoul does not appear as a valid option, you have to choose it manually from the list of every frame and when you do it says you don't have two levels in kobold's license. Secondly the tar pit full action states: "Choose up to two objects of size 2 or smaller in range 10. The Infected Apocalypse Rail melts them with a spurt of molten slag. They are destroyed and replaced with an area of Difficult and Dangerous Terrain that deals Burn" how much burn tho? And lastly the active ability says that your terraforming is a quick action now, even though terraforming is an active ability of the kobold frame, i assume it means that the passive is a quick action?
I hope this helps!