Personally, I have trained in Lerdrit (Lerd-lit, for those who don't know Thai Engrish pronunciations); combining that with some sparring practice with SEALs, being trained in some of their lethal and crippling takedowns. The combination can be rather nasty because Muay Thai can slip into someone's defenses and block counterattacks while setting up for something that the poor victim will feel for every cold winter for the rest of their life, if they live. Muay Thai tends to be a bit slow but powerful, which can be used for an unpredictable change-up into a crippling strike and clinching moves that turn into grapples. Cut kicks are also pretty nasty. Which is probably why they like to teach Lerdrit to the SEALs and some ranger units.
As a result of sparring, though, I have some seriously scarred up shins.
As a result of sparring, though, I have some seriously scarred up shins.