A pretty simple technique would be the "questionmark"-roundhouse kick. That should be what Don$ukh refers to as Mawashi Geri from Karate. Actually Mawashi Geri means basically just "roundhouse kick" and there are different ways to execute it, one of them being the "?"-way, which is quite common in Karate, but not so common in kickboxing so kickboxer tend to get easier surprised by it.
The execution is simple: you don't start the kick like in the circular motion of a roundhouse kick, but rather like a straight front kick. Then, when your knee is about waist high you turn your hip and let the foot follow in a circular motion when extending it. Hence the motion looks like a "?".
You get a good impression particularly at 1:11 and 1:23
It doesn't have the same power as a regular roundhouse kick, but due to the surprising effect it has quite good chances to land and still has enough power to KO people who didn't expect it.
A simple set up for that kick can be throwing a couple of powerful front kicks to the mid section, so your opponent brings his guard to the center. Then you do that "questionmark"-kick, faking a front kick, but in reality turning it to a roundhouse kick to his head.
A sneaky set up for a front kick is to do the kick out of a Capoeira ginga (basic step) motion. It's nothing you could use all or most of the time, but when you get a feeling for when to use it, you'll get an almost 100% hit ratio. You can use it for example, when there is this little non attack pause after your opponent has attacked and he slows down a little to pace himself. Then you do 3 or 4 steps of the ginga and at your last step instead of bringing your foot back again, you throw your straight front kick (with the liver being a good target).
You can surprise most opponents with that set up, because it completely breaks the usual fighting rhythm. The ginga move itself is really rhythmic, but you do only long enough for your opponent to get the rhythm and expect you to step back with your last step, but before he can capitalise on it you do the opposit of what he expects.
Like this, but incorporating a more kickbox style front kick:
When your opponent has a stance with his feet rather close together, another sneaky set up is to throw some decent low kicks, then faking another one, but when your opponent lifts his leg to check it, instead of going again for the front leg you drop your level and kick below his lifted front leg and aim for the back leg. The execution can be either a low kick to the calf or ankle area or it can be a sweet. But be careful with that in training as your training partners could easily twist their ankles if you kick with too much power.
On the defensive side there is a variation of checking the low kicks, which is often used in Kyokushin: instead of checking the low kick hard with a stiff lower leg you can take the incoming kick rather soft with your lower leg being like a spring and then pushing and thereby redirecting your opponents kicking leg. Especially if your opponent is only used to hard checking low kicks, there are good chances that he'll end up in a bad stance maybe even unbalanced, so you can capitalise on it with a following counter attack. This technique needs quite some practice to get the timing right, but even if your timing is wrong, you have at least your leg up and can still check the incoming almost the regular way. So it's not an either or, but just an additional method to defend against low kicks.
There are a lot more nice sneaky techniques, but at least the first three I discribed are quite easy to implement even for intermediates or beginners.