Hard fight even on lower difficulties. My method was as follows 1. 3 Melee characters-1 Fighter, 1 Paladin, 1 Bard Guy; 3 Casters -1 Cipher (me), 1 Wizard, 1 Priest 2. Close formation with a melee on 3 sides and a wall at the back. 3. Potions at the ready, rest in the Inn before hand and eat some food. 4. Place a trap if you have one. 5.Use one of your melee to trigger the fight then run back to formation without getting engaged. 6. The spirits will try to take out your cipher as they are weak to mind attacks; so your priests job is to stay next to the cipher at all times. 7. Get cipher to dominate one of the purple spirits 8.When bard is ready summon skeletons as fodder to block holes in your formation. 9.Buff everything 10.Try create a front line and use your wizard to to weaken them with disabling spells on this front line. They key in this battle is controlling the battlefield, never letting the spirits at your casters, don't let your melee get bogged down move them back to protect your casters as needed. Save your knockdowns etc to disengage from your casters, especially any Ciphers - they are strong against spirits and will be prime targets.
Jay Peg replied to micin3's question in Pillars of Eternity: Technical Support (Spoiler Warning!)I got this issue as well in the Keep Sewers notfar from where you enter. The work around I used is to knock the party member prone, I did with with fighters knock down abilty, when the stuck character is down give it a new location to go to and keep clicking. I did this and it works straight away.