The Manari Crusader

First you must artifice 'a functional summoning beacon' to summon the boss. This requires:

• a summoning stone - purchasable from magic shops.
• the lace gloves of the Vizier Mataan - purchasable from Lady Undya (1350 qp)
• a summoned shiv - have a second class kill Klemanak, the Conjurer (chance to drop)
• a summoning beacon - drop from Mourdul, Throne of Pain
• a staff of summoning - drop from a necromancer in Catacombs of Shame.

Given that you need to be in Mourdul's area anyway to fight the Manari Crusader, it's best to obtain the summoning beacon last and artifice there to summon the boss.

After artificing the functional summoning beacon, head to the west side of Mourdul's area to be able to wear the item. Hold and use.

Encounter

Boss can be easily soloed. Does not cast nor emotes damage and only occasionally throws bombs, or disarms.