!markov is an API call. What script are you using for this command? If you could give a more concrete example of what you are trying to accomplish, this might be easier to answer. Of the top of my head, the answer is likely "no", that an API command can be triggered by an API Command Button within a Roll template, but not deliver results within the template itself. But if you could explain more, it might help to understand the problem you are trying to solve.