"The last stronghold of the elven rebels is like a tumor in the forest. It must be uprooted."
Forest Fortress is a dungeon which unlocks at level 30. Its drops are Iseer shards, Elf Prophet and other Epic cards, 40 gold, Steel and Magic Essence. It requires 25 stamina in total.  

Round 1 faces Tiana with 65 HP who spams Pegasuses and has the weapon "Destroyer" 3MP: Give target unit +2-3 Attack and Armor Piercing. All damage is physical, so armor isn't a bad idea. Enemy units are: Pegasi Scout, Pegasi Charger, and Pegasi Captain

Round 2 faces you against Head Priest Fyero and Elite Ranger Riego. They both start at 50 HP. Fyero has "Blessed Staff", 3MP: All units minions +1 or +2 HP. Riego has "Double-Strike" which is 3MP: Deal 2 PDMG to all enemy units. They go enraged when the other dies, and will spam their weapon unlike when they're unenraged.  

They do not use any Pegasus and spam other elf units like Elf Sniper and Elf Apprentice. Ranged units are physical, non-ranged tend to deal magic damage.