The Metamorph counter index is a special type of metamorph index. It has all of the features of the normal Metamorph index, but in addition supports the LIKEIN query. If you are using LIKEIN then you should create a metamorph counter index. Using LIKEIN is most useful when you have a large number of queries, anywhere from 10,000 to over a million. Without the metamorph counter index Texis would effectively have to run each query against the document, which is what you are trying to avoid with LIKEIN, <profiler>, and the metamorph counter index.