Multiplayer

Finally, you can farm souls through invasion and jolly co-operation. As a gold or white phantom, the amount of souls you would obtain is a percentage of what your host would obtain. As a blue, purple, or red phantom the amount of souls obtained is a percentage of how many souls were required for the target to reach their current soul level. More details can be found here:

https://www.reddit.com/r/darksouls3/comments/4fn3f1/first_batch_of_testing_results_how_souls_are/

A quicker method is to ask another player to drop soul items for you. The host can drop 7 stacks of 99 Souls of a Great Champion, 7 stacks of 99 Souls of a Champion, 7 stacks of 99 Souls of a Venerable Old Hand, 7 stacks of 99 Souls of an Old Hand, and 2 stacks of 99 Large Souls of a Seasoned Warrior. These come to 30 stacks, totalling 75,982,500 souls. Ask someone to drop these 30 stacks of soul items and summon your red phantom. You can gain extra souls by killing the host and equip all soul-boosting gears: Symbol of Avarice, Silver Serpent Ring+3, Shield of Want, Mendicant's Staff. The effects of these soul-boosting items stack with each other in a multiplicative manner to give you 100(1.50 x 1.35 x 1.20 x 1.20) = 291.6% extra souls. For maximum extra souls, the host should be at SL802. A red phantom killing an SL802 host would obtain 1% of the souls required for the host to level up from SL801 to SL802, i.e. the red phantom would obtain 1% of 12,368,992 which is 123,689 souls. Equipping the above soul-boosting items would yield 360,677 souls from killing an SL802 host. The above method should provide you with a maximum of 76,343,177 souls per round.