In the arena you have 4 banners, pick any of them. To activate one, go up to it and knife the rope keeping it rolled up. It will open up and give you a challenge. Complete all 9 to get this achievement. To turn on In, go to the podium in the centre of the arena and press X on your designated corner.
The challenges are as follows and can be in a random order.
- Kill 6 Zombies with equipment (Grenades etc)
- Knife Kill 13 Zombies
- Kill 9 Gladiators
- Headshot kill 5 zombies in a row.
- Kill 5 Tigers
- Stop 3 catalysts transformations (Kill zombies during the mutation into the elemental zombies)
- Slide under the blade trap without being hit. (In The Pit.)
- Complete 1 full round inside the Temple
- Destroy 9 pieces of armour from the special zombies.
- Kill a blight father while being pulled by its tongue
- Have max crowd affinity for 2 mins (The green hand will have green flames coming from it when at max)
- Get the final blow to a Blight Father (The big yellow spider looking things)
- Kill 9 zombies with the Brazen Bull (This is the shield. 3 pieces to find to craft it. One in Ra Temple, One in Zeus Temple, One in Odin Temple. Craft in Pit.)
- Kill 9 zombies with the Death of Orion charge shot. (Use this guide to get it