Ranger – “Emerald” [5th campaign, 2nd mission]

I completed it! You just need to spend 2-3 weeks building up your army, and THEN storm the Castle located in the north, then the castle in the west (very difficult, but achievable), and then the castle in the east. I recommend having two heroes.

Added 2 minutes ago
Army:
!Elven Archer - 60 units.
!High Druid - 40 units.
!!!Ancient Ent - 60 units (recommended).