BS2 SL1 DLC3 Boss 6

Done without leveling up, taking any stat-up souls, or going into Chaos Dungeon.
Covenant is Margaret
Turn 1: Switch to Anchor a then cast INDIGNATION. Switch to Sword of Giants and cast ABSOLUTE PRECISION and HAMMER. Then switch to Wand of R'lyeh and Cast SPIRITUAL UNITY. Then Switch to Wand of Creation and cast GHOSTFIRE. He blinds you.
Turn 2: Switch to Sword of Giants and then use HAMMER. Switch to Jabber's Scythe and use SOUL BREAK and CORPSE DRAGON'S COERCION. Then switch to Wand of R'lyeh and cast SPIRITUAL UNITY. Then switch to Wand of Creation and cast an %damaging spell. If you have an extra turn from Serpant God's Blood then use acid rain or the other spell that does percentage damage. If you want no RNG replace CORPSE DRAGON'S COERCION with REQUIEM or a REQUIEM item and the last action with defend. Otherwise, you have a 50% chance of being killed here
Turn 3: Switch to Sword of Giants and use HAMMER. Switch to Jabber's Scythe and use SOUL BREAK and CORPSE DRAGON'S COERCION, Switch to Wand of R'lyeh and use SPIRITUAL UNITY. Switch to Wand of Creation and cast MEAT SHIELD and GHOSTFIRE. Again, replace CORPSE DRAGON'S COERCION and last action with defend if you don't want RNG. Otherwise, another 50% death.
Turn 4: Switch to Sword of Giants and use HAMMER. Switch to Jabber's Scythe and use SOUL BREAK and CORPSE DRAGON'S COERCION, Switch to Claymore and use the 5%HP damage skill. Switch to Wand of Creation and cast GHOSTFIRE.