This Diablo 4 War Plan setup turns Whispers into an experience and loot goldmine
Combine Mystery caches with Varshan Ambushes and 50% more Experience Orbs, and your Whispers will shower you with rewards.
It is almost mid-season already, and now that you spend your time farming for all the different secrets Diablo 4 Season 15 has in stock, you might want to focus more on simply leveling a new alt or getting your Paragon level closer to 300. Well, it turns out Diablo 4 players are finding a pretty ridiculous way to turn Whispers into an XP farming machine, and it all comes down to using the right War Plan at the right time.
Rob published a video where he explained this new farming strategy that combines fast Whispers, Varshan ambushes, and a temporary War Plan setup. The result is a farming loop that can generate huge amounts of XP, Mythics, materials, boss encounters, and 
Resplendent Spark. In his video, he used a new solo character and went up to Paragon 262 after around 20 hours of doing this. He also estimated reaching Paragon 300 in around 40 to 45 hours, but that remains to be tested. It is still a lot of hours, so do not expect to reach max Paragon in one day either.
The Trick Is Swapping Your War Plan
This strategy relies on switching your War Plan depending on what you are doing. When you are farming, you use the War Plan nodes that improve caches and activate Varshan Ambushes for more, and when you are ready to open everything, you switch to a War Plan that increases what you get from these boxes.
The War Plan respec costs 50 million gold, but the farm produces enough gold and other rewards that should easily make this manageable. But this means that you do not want to open your caches every time you hand in whispers. You keep them in your stash until you have one or two full tabs, then you swap your war plan and open them all at once.
Here are the two different plans you need to swap between:
So basically, you first farm Whispers with the Grim Mysteries and Malignant Invasion nodes active in order to get Mystery caches and Varshan Ambushes for additional rewards. Once your stash is full, swap Grim Mysteries to Wisdom of Whispers and Resplendent Favor and open all your caches. Now all you need to do is spend the next hours sorting through the amount of loot you just got.
Just Farm the Fastest Whispers
If you really want to focus on farming Whispers for a few hours, you do not need to do anything complicated. The idea is to check the map and grab whichever Whispers are quickest and closest together. Helltide rituals, events, short dungeons, caves, and boss Whispers can all fit into that. Those are completed in a few seconds, and you can chain them easily.
The result is basically:
Grim and Invasion War Plan Setup
Farm quick Whispers
Save the caches until you have a full stash tab
Swap your War Plan to the XP one
Open everything
Repeat
Keep in mind that this strategy also works so well because we currently have the Whisper Tree event running. You will get less XP once the event is over. So if you are looking to push Paragon, do it this week before the event comes to an end.