We will have 4 contracts for Survival and Arcade during the Viking 2022 event. Here is a small explanation on how to reach the end reward, "Viking 2022 Skinbox".
The most important contracts are the first 3. You have to finish these missions to get a Viking stone as a reward. So basically 3 contracts are there to collect these stones and the 4th one is to exchange the stones for the Skinbox in the trading lounge (Arcade) or Blue Ridge Safe Zone (Survival).
To complete these contracts, you need to kill Zombies with melees such as Hatchet, Sword of the King or the Spear of Blood.
Where can you find all these melees and contracts? There are Viking crates all of the maps which you can open and loot. Some spots are Viking-themed but you also have a chance of just finding crates randomly across the map.