This Diablo 4 item can skip the worst part of the Secret Cow Level grind
The Bell of the Bovine can summon cows for you, speeding up the quest's most annoying part.
If you have been putting off Diablo 4's Secret Cow Level because of the ridiculous amount of cow hunting involved, Season 15 just gave you a much easier way through the worst part. The 
Bell of the Bovine can now drop from Moophisto, and its special effect does more than summon exploding cows for a bit of extra damage. And yes, sorry, this involves a lot of cows... But at least you can finally stop wandering around looking for them and make the Bell do the work for you.
666 Cows Killed in No Time
The Bell of the Bovine has a chance to trigger a Moo when you hit enemies, and that can then summon an exploding cow. The important part is that killing these summoned cows counts toward the requirement needed to obtain the three relics for the Cow Level questline.
So instead of repeatedly finding small groups of cows and waiting for them to respawn, you can equip the Bell and simply fight enemies in a high-density area. Helltides are particularly useful for this, since you constantly have a ton of enemies there, and it gives the Bell plenty of chances to summon cows. Just make sure you are farming in the right region for the relic you are trying to obtain.
Because yes, the cows still need to die in their specific regions, otherwise the items will never drop:
Bloody Wooden Shard: Kehjistan or Hawezar
Intricate Metallic Fragment: Dry Steppes
Musty Tome: Fractured Peaks or Scosglen
Once your 666th cow is killed, you get the relic associated with the region you are currently in. Move to another required region for the next one and repeat the process until you have all three.
You Still Have to Finish the Cow Level Quest
The Bell does not magically unlock the Secret Cow Level by itself. It just removes the first step that is a little bit annoying. After collecting all three relics, you need to take them to the fountain in Ked Bardu to cleanse them. You can then use the cleansed relics with the corresponding oxen statues to obtain the Strange Key.
That key opens the Forlorn Hovel, where you will need to continue working through the cow-related objectives and obtain the 
Stamina Potion. From there, there are still a ton of additional steps before you finally gain access to the Secret Cow Level, including combining the required items in the Horadric Cube. You need:
A Rusted Bardiche (made from Jabbering gemstone, Rusted Old Bell, and Crooked Staff)
Neyrelle's Hand (made from Father's Chains, Mother's Rose, and Hierophant's Skull)
Throw the Stamina Potion, Rusted Bardiche, and Neyrelle's Hand into the Horadric Cube to get the Trophy of the Faithful
Open the trophy and get the "Moo" Emote and a Torn Page
Wait for a Tuesday and take the Boat at the eastern shore of Cetos in Skovos where a Boat awaits you
The Boat will drop you on an Island. Over there, head inside the cellar where you will find a bunch of cows and a ritual site
Slaughter the cows and the portal to the Secret Cow Level will open
After that, you pretty much just have to kill Cows. Of course, if you have a friend who already has access, they can also simply "Moo" at you with the Emote, and it will open a portal in another location for you.
So keep in mind that the Bell of the Bovine is not a complete replacement for the Cow Level questline. It is a shortcut through the first requirement, but you still have hours of grinding to do in order to access the Secret Cow Level.
How to Get the Bell of the Bovine
The Bell of the Bovine is a Unique Amulet that drops from Moophisto. It is not guaranteed, so you may need to kill him multiple times before getting one. Moophisto requires 5 Prime Ribs to summon, but there are usually plenty of players around the boss who are willing to summon him themselves. If you are already working toward the Secret Cow Level, it is worth getting the Bell first.
Once you have it, the 666-cow requirement becomes considerably less painful. And if you have already unlocked the Secret Cow Level, well... at least now you have a magical cowbell.