Souls are the most annoying and cheapest enemies in the whole game. Unlike many of the super tough event bosses and even Mini monsters these have no chance of dropping HP and there is no reward for combating them. Prior to the recent updates (the core update and the current one) souls wouldn't spawn when the party was full.
http://forums.spiralknights.com/en/node/109725
http://forums.spiralknights.com/en/node/109859

This greatly encouraged players to work together to make missions easier, so much so that souls became an almost non-existent threat (Which everyone liked). Now the souls can spawn in a party of any size, this makes certain missions to become extremely laggy and when dealing with Core or Danger missions lag is something that can be the cause of death.

In addition to eliminating souls from full parties I would like something done about their spawn origins. At the moment souls can spawn anywhere on the screen, even in front of the player. Often souls spawn in front of a player and immediately explode, sometimes they are invisible and the player doesn't know about them till they have taken damage and possibly got statused. Sometimes souls appear to be a mile up in the sky only so move and inch and reveal that they are much closer than they had appeared (prevalent in Dreams and Nightmares).

Eliminate souls from full parties, make it so they can't spawn in the player's immediate vicinity, fix the bug with them being invisible, and that bug in Dreams and Nightmares.

Till then I'm not going to waste my time on any of these missions because I don't like having my HP stolen just because an invisible souls decided to spawn in front of me and pop.