Pit of Heresy

Symbols

Source

The Necropolis

Go to first symbol and check other symbols you need. Then go and kill minibosses in correct symbols.
Oracle (Shrieker) - Kill with block
Omen (Wizard) - Kill with range
Might (Knight) - Kill with melee

Tunnels of the Despair

Source

Chamber of Suffering

You need 6 balls to dunk and not let totem kill you. Have very very good Ad Clear build. (For example: Forbearance) And don't let knights on the ceiling kill you. (2 spawn every ball)

The Harrow

Source

Zulmak, Instrument of Torment - Cradle of Damnation

Kill mini bosses -> Kill Boss
When boss is vulnerable, be aware of cursed thrall that spawn on 3 small pillars. (2 cursed thrall each pillar)