I’m getting 720 per warlord 4 explore with valkrie and celestial armour with acolyte. It allows more control of the board too. I could put a second necromancy traited troop in, but that’s not quick and not worth it just to raise the soul cap slightly.
Warlord 4 with celestial armour… Lots of souls and pretty quick battles if you have all kingdoms maxed. (your troops would be powerful enough to breeze warlord 4 most of the time, if not put it on warlord 3)
Warlord 1 is your best bet when farming souls. You will get through matches 2x as fast as Warlord 4. And only slightly less souls per battle so that = more souls per hour.