I was wondering which Northern Mantis styles have ground fighting in them. I know 8-step has Ground Mantis or low mantis which only GrandMaster Sun knows.
Kagerou
Low Mantis.
I think Low Mantis and The grappling he taught to Joel Sutton are different. I also heard through the Grapevine that Master Sun used to train a midget Sifu Student. Master Sun felt sorry for him so he taught him some Low Mantis to better protect himself only to later find out that the midget already had a master that sent him to leach techniques 
Who knows maybe it was Dr. Evil 
From what I know Low Mantis is balls to the floor fighting stance and takes 5 times the leg strength than I currently have. Its kind of in-between stand up and groundfighting and af far as anyone knows, no one else has anything like it. I’ll eventually get to learn it, but I’ll be in my late 30’s by that time 
8Step Sifu
Tai Chi Praying Mantis Ground Mantis
There is a Ground Mantis in TCPM at the advanced level. This form is dynamic and demanding. However, there are different versions in certain moves available to suit the technical and fitness level of the student. Technique wise it has combinations on takedowns, taking falls, grappling, etc.
Mantis108
Contraria Sunt Complementa