Skulls have been a part of the Halo series and this is true for Halo Infinite. Veterans will know what these collectibles are, but newcomers to the series may not know. Skulls are hidden collectibles that can be turned on to alter gameplay. There are 12 skulls in Halo Infinite and the second is the Cowbell Skull.
The Cowbell Skull is found in the mission Foundation. After you retrieve Weapon, your AI companion, you will watch a cutscene. You will then carry on with the mission, coming to a room with some Grunts and Jackals as well as some large pillars. Kill them and then head back to the entrance of the room. There are several large support pillars in the room, go to the first.
Related: All Halo Infinite Skulls Locations
You will see at its peak a beam in the center of the room. Use your AI scan and the Cowbell Skull will illuminate. You will need to use your grapple to make your way up here using the gaps and ridges on the pillars and beam. If you fall, the restart is fairly short. Keep trying until you get up to the skull and collect it.
The Cowbell Skull will speed up your recovery time from explosive damage once it has been activated. This works well with the Boom Skull but is helpful in general.
For more information on Halo, check out Where to find the first Skull location in Halo Infinite Campaign – Boom Skull and Entire Halo Infinite Campaign mission list on Pro Game Guides.