the last boss fully upgraded taking too long to kill! I suggest lowering it's hp and boost its attack. I've fully upgraded everything and it'll take me about 30min-1hr to kill it..
1. only create battle quests till the first boss
2. aim for 1 sec respawn for adventurer and fighter
3. upgrade the first 2 quest accordingly (damage vs health and armor)
4. rush for 1 sec respawn mage
5. spam upgrade mage
6. max everything in under an hour :(