This is the 'King Godd' achievement:
Deafeat King Godd and complete the 'King Godd' quest.
Once you have completed the first quest, you will gain a key, which will allow you to enter an area that was locked before.
Once you have reached this area, you have to defeat a goblin that is bullying another goblin (Gibbins). Gibbins will give you another key, as well as some treasure. Follow the directions given and you will unlock the Royal door and climb two ladders (fighting enemies along the way) until you reach King Godd's room.
He is busy eating, which makes it fairly easy to defeat him. He is the slowest enemy so far, giving you multiple moves per turn. This allows you to set yourself up for 4's and 5's for extra turns, and max out the gems you need for your best spells.
He does have a few good attacks, so try to defeat him quickly and stop him collecting the gems he needs. You should have no problems, but if you do, ask a question below, and I will try my best to answer.
Good luck.Please either comment below or send me a Personal Message if you have any comments or improvements.