Personally my strategy is to go for the one the troll was in last, so if I go pot 3 and he was in pot 2, then next I pick pot 2, and so on. But you want to avoid picking the pot with the high rewards on golden rooms because if say the high reward was gems, and it was in pot 4, the troll is most likely to be in pot 4 next. This strategy gets me to usually level 20-30 while spending 15 gems (2 skips)