Similar to Drowned Caverns: Arena of Heroes, this instance is an arena-event that tests a player's might against increasingly difficult opponents. Should the player be triumphant against all challenges, they will be crowned champion and rewarded with new armor and unique vanity items.
The zone is a controlled-ring-event; simply talk to Fip Slytail to initiate the event, and every time thereafter defeating a challenge. If you are having trouble clicking on Fip Slytail then tab target him and /hail to initiate dialogue. The list of challenges is as such:
Speak to Fip Slytail a final time and select the last dialogue option stating that you would like your prize and would like to return to Splitpaw Den. Kill the treasure chestmimic that spawns at the center of the arena and it will drop an actual Treasure Chest containing various equipment items and two guaranteed drops:
If you choose 'difficult' upon entering, you'll get mobs 2 levels higher than normal. If you choose 'very difficult', 5 levels higher.
Mobs do not scale with the players above level 50. If you are above level 50 and mobs are grey, you will receive no reward, however, you will still be able to advance the questline for A Darkened Shard, Part 2. After each challenger a note will display at the top of your screen telling you that you have trivialized the arena and no reward will be offered and the final fight with the mimic treasure chest will not happen.
If you want additional mounted dreadsnout heads, then simply zone out of the instance after looting it and then zone back in. Speak to Fip Slytail again and ask for your prize. Another treasure chest mimic will spawn in the center that will drop an actual treasure chest that can be looted. You can repeat this process ad nauseam.