Magic chest

The Magic Chest is a purple-glowing chest located at the entrance of the Grand Exchange and outside the duel arena. The Magic chest is used to initiate the rune-suduko game.

Sudoku
You see a 9x9 grid of 9x9 cells. Each cell in the grid needs the following in it:

One Air rune, one Fire rune, one mind rune, one body rune, one chaos rune, one earth rune, one law rune, one death rune and one water rune.

'Each rune may only be put once in each 9x9 cells, and only once''' in a horizontal line or a vertical line.

Completion & Rewards
Once you think you completed the puzzle, you can click the 'Open Casket' button. If you have made an error, it says that the puzzle isn't completed yet.

When you click the button, the pop-up will close and you will get a reward, when your inventory is full, the reward will be placed automatically in your bank.

You can win the following rewards:

Seeds of different types.

Herbs of different types.

Talisman Staffs

Runes of different types (usually not many)

Inferno Adze (the rarest loot).

Cosmic boots, gloves or body (rare)

Shark gloves (rare)