Completing stages in Salad farm yield great exp for your user level. If you are able to take down “Expert” map that will be even better.
Do use gems to replenish your energy.
(Note: There a max cap to how many times you could replenish the energy.)
Due to recent patch the cap have been removed
Within a day duration we were able to level from user level 18 to user level 28.
That is not all, when completing these stages you will also receive exp monsters to level your heroes as well.
Good luck and happy leveling.