Nice, I hadnt thought about the weekly dungeon for soul farming! Not sure if its better or worse, but farming lol does drop the odd rare soul.... Otherwise, dropping the common souls from LoL farming can also get you a decent amount of 3* sacrifice fodder and even better that they shard up to a rare. My advice though is just to sell the 2 and 3* as its so much faster than painstakingly saccing 100s ofr 2* chars for not much return.