Darkest Dungeon II

The Lost Crusade is a quest that comes with the Binding Blade DLC and, when completed, unlocks the Crusader for recruitment aboard your coach. It is not terribly difficult, but has quite a few steps that must be completed in a specific order to proceed, mostly by carrying special items to designated places. Note: if you die or abandon an expedition, you do not lose progress on the Lost Crusade. On your next expedition you will be given the most recent item and can proceed from there.

Step 1 (first inn): When you reach the first inn (after the Valley), you will be given the Battered Helm, a stagecoach trophy. Mount it in the trophy slot to proceed. Note: you cannot proceed in this quest without the Helm always equipped. Keep it in this slot each time you die to progress the quest. It will not stop you from facing the Mountain boss (which requires a lair boss trohpy equipped), which I will explain later.

Step 2 (any region): Look for road battles, which have a red icon on the map and only appear between nodes. The one you want has barricades (2 barricades and 2 bandits). Defeat the encounter to receive the Tattered Banner, a combat item. No need to equip this item yet unless you're already in the Tangle.

Step 3: Enter the Tangle as soon as the opportunity presents itself. Would recommend equipping the Tattered Banner now so you don't forget to later. Look for resistance encounter nodes with the Lost Battalion and choose combat. In the fight, use your Banner item on the Bishop enemy. This will give the Bishop a serious buff, so be ready for a tougher fight. Upon completion you will receive the Unique Reliquary, a deliverable item.

Step 4 (any region): Make it to the next inn and you will automatically trade in your Reliquary for the Sanctified Scroll, a stagecoach item. Equip the Scroll.

Step 5 (any region): Look for an assistance encounter, this is where displaced peasants can give you treasures throughout a region. With your scroll you will get a unique choice, do that to get the Rumour of Riches, a currency item.

Step 6 (any region): Look for the hoarder, the wandering merchant. With the Rumour in your inventory he will have a special treasure in his shop, the Blessed Blade deliverable. Buy it.

Step 7 (any inn): Upon arrival, your Blessed Blade and Battered Helm will automatically combine to form the Helm and Blade, also a trophy. Equip it to your coach.

Step 8 (any region): With your new trophy equipped, the final region fight (normally called Oblivion's Ingress and populated by cultists) will become a unique fight called the Caged Knight. Select combat of course.

Step 9: Your final task is to defeat the boss of the Caged Knight: the Warlord. This is a challenging boss and I would recommend having a way to clear combo tokens from your heroes. If you don't do that, he will hit you with an attack called Ferox Impetus that will do 10+ damage to 3 of your heroes. Between this and his other attacks, which can stun and debuff, he can take down even the tankiest frontliners. Keep up the DoT on him as he can take multiple turns every round (except bleed, he is resistant to that). Debuff/stun resistance are also recommended.

Once you've defeated the Warlord, the Crusader and this cheevo are yours! The Warlord will become a wandering miniboss throughout future runs, and his drops are worth the risk to engage him in my opinion.