A KEY QUESTION IN ASTROPHYSICS IS TO CONSTRAIN THE EVOLUTION OF THE LARGEST GRAVITATIONALLY BOUND STRUCTURES IN THE UNIVERSE. THE SERENDIPITOUS OBSERVATIONS OF SWIFT-XRT FORM AN EXCELLENT MEDIUM-DEEP AND WIDE SOFT X-RAY SURVEY WITH A SKY AREA OF ~160 SQUARE DEGREES AT THE FLUX LIMIT OF 5E-15 ERG/S/CM^2. THIS SURVEY IS ABOUT AN ORDER OF MAGNITUDE DEEPER THAN PREVIOUS SURVEYS OF SIMILAR AREAS AND AN ORDER OF MAGNITUDE WIDER THAN PREVIOUS SURVEYS OF SIMILAR DEPTH. IT IS COMPARABLE TO THE PLANNED EROSITA DEEP SURVEY BUT ALREADY WITH THE DATA SEVERAL YEARS AHEAD. THE UNIQUE COMBINATION OF THE SURVEY AREA AND DEPTH ENABLES IT TO FILL IN THE GAP BETWEEN THE DEEP PENCIL BEAM SURVEYS (SUCH AS THE CHANDRA DEEP FIELDS) AND THE SHALLOW WIDE AREA SURVEYS MEASURED WITH ROSAT. WITH IT WE WILL PLACE INDEPENDENT AND COMPLEMENTARY MEASUREMENTS ON THE NUMBER COUNTS AND LUMINOSITY FUNCTIONS OF X-RAY SOURCES. IT HAS BEEN PROVED THAT THIS SURVEY IS EXCELLENT FOR X-RAY SELECTED GALAXY CLUSTER SURVEYS BASED ON OUR INITIAL ANALYSIS OF 1/4 OF THE FIELDS AND OTHER INDEPENDENT STUDIES. THE HIGHEST PRIORITY GOAL IS TO PRODUCE THE LARGEST UNIFORMLY SELECTED CATALOG OF X-RAY SELECTED CLUSTERS AND INCREASE THE SAMPLE OF INTERMEDIATE TO HIGH REDSHIFT CLUSTERS (Z>0.5) BY AN ORDER OF MAGNITUDE. FROM THIS CATALOG WE WILL STUDY THE EVOLUTION OF CLUSTER NUMBER COUNTS LUMINOSITY FUNCTION SCALING RELATIONS AND EVENTUALLY THE MASS FUNCTION. FOR EXAMPLE VARIOUS SMALLER SCALE SURVEYS CONCLUDED DIVERGENTLY ON THE EVOLUTION OF A KEY SCALING RELATION BETWEEN TEMPERATURE AND LUMINOSITY OF CLUSTERS. WITH THE STATISTICAL POWER FROM THIS LARGE SAMPLE WE WILL RESOLVE THE DEBATE WHETHER CLUSTERS EVOLVE SELF-SIMILARLY. THIS IS A CRUCIAL STEP IN MAPPING CLUSTER EVOLUTION AND CONSTRAINING COSMOLOGICAL MODELS. FIRST WE PROPOSE TO EXTRACT THE COMPLETE SERENDIPITOUS EXTENDED SOURCE LIST FOR ALL SWIFT-XRT DATA TO 2015. SECOND WE WILL USE OPTICAL/ IR OBSERVATIONS TO FURTHER IDENTIFY GALAXY CLUSTERS. THESE OPTICAL/IR OBSERVATIONS INCLUDE DATA FROM THE SDSS WISE AND DEEP OPTICAL FOLLOW-UP OBSERVATIONS FROM THE APO MDM MAGELLAN AND NOAO TELESCOPES. WISE WILL CONFIRM ALL Z<0.5 CLUSTERS AND A FRACTION OF Z>0.5 CLUSTERS. WE WILL USE GROUND-BASED OBSERVATIONS TO MEASURE REDSHIFTS FOR Z>0.5 CLUSTERS WITH A FOCUS OF MEASURING 1/10 OF THE SPECTROSCOPIC REDSHIFTS OF Z>0.5 CLUSTERS WITHIN THE BUDGET PERIOD. THIRD WE WILL ANALYZE OUR DEEP SUZAKU X-RAY FOLLOW-UP OBSERVATIONS OF A SAMPLE OF MEDIUM REDSHIFT CLUSTERS AND THE 1/10 BRIGHT SWIFT CLUSTERS SUITABLE FOR SPECTRAL ANALYSIS. WE WILL ALSO PERFORM STACKING ANALYSIS USING THE SWIFT DATA FOR CLUSTERS IN DIFFERENT REDSHIFT BINS TO CONSTRAIN THE EVOLUTION OF CLUSTER PROPERTIES.