The priests and the diviners together made up the religious authorities of the Philistines.1 Diviners would be those who seek to discern the will of the gods and try to look into the future. Such practices were prohibited under Mosaic law (Deuteronomy 18:10–14) but they were popular in the ancient Near East.2
1 The ark of the LORD was in the country of the Philistines seven months.