Back 4 Blood’s Tunnel of Terror expansion adds Ridden Hives to the experience. These side levels in the Campaign will have lots of opportunities to loot better weapons and attachments as you proceed through them and task you with gathering a new currency called Skull Totems. There are three Skull Totems in each Ridden Hive you need to carry to the end. Here is how to combine them.
As stated above, there are three Skull Totems in each Ridden Hive. When you pick up one, it acts as a melee weapon that drops on the ground when you switch to your other weapons. Having three Cleaners with their hands full of melee weapons is not necessarily something you want, though. Instead, you should pick one person on the team to carry them. All they need to do is walk up to another Skull Totem and interact with it. They will stick the new skull alongside the one they already have.
When you combine Skull Totems, you are actually making the melee weapon better as well. Each skull adds 30 damage onto the weapon, so if you have all three on, you are swinging a legendary stick worth 90 damage per swing, a pretty massive hit for any Ridden that gets too close. Make sure they are in your hand when you leave the level, and you will add them to your totals.
Read more on gamepur.com