So, in the context of striking, what is a combination?
I say a combination is not picking three basic strikes and practicing stringing them together so that they become one neuromuscular program. You don't pull the trigger and automatically these three techniques happen in sequence. (That is a very basic form of combo, but not what I'm talking about.)
I say that skill in throwing combos comes in developing the ability to throw one fundamental technique, then rapidly assess, "What else useful can I do from this position with this momentum while I am returning toward guard or neutral?" Basically taking targets of opportunity.
So, a good combo is not, "Do inside hammer, then front kick, then shuto to neck, then back away." Instead, a better combo is, "Ok, I have hammered his attacking arm and I am moving away from him so I might as well check this arm and that leg and chop the neck in passing." Or another combo from this position might be, "I've hammered his arm and am moving away... How about I rake across his eyes and then push myself away from him with a reverse punch to center of mass." Situational things strung together appropriately in the moment.