Best adventure for gaining most xp?

[Ahileus]

I finally cleared my home island so now I need to level up so I can build more experienced units like Elite or XB...

So my question is what is best and cheapest adventure for gaining lot of xp points (and so leveling up faster)?

[K0sh1]

At your level you can try doing Dark Priest or Witch of The Swamp and work towards Stealing from the Rich