Bone Dust x5100 (stacks to 5.1k)
Defeat enemies at /battleunderb (this will generally be faster in a private room). You will earn Undead Energy as you do this.
Undead Energy x10k (stacks to 10k)
If you haven't gotten all 10k Undead Energy by farming Cavern Celestite and Bone Dust, just keep killing at /battleunderb.
Primarch's Hilt x2 (stacks to 3)
Defeat Colossal Primarch at /bosschallenge. Unless you want to solo this with Chaos Avenger, Void Highlord, or a dodge class like Yami no Ronin, do this with a group.
Blade Essence x2 (stacks to 2)
Defeat Chaorrupted Armour at /chaoscrypt (~1% drop rate).
Chaorrupted Hourglass x31 (stacks to 31)
Defeat Chaos Lord Iadoa at /timespace (~20% drop rate). Complete Iadoa's 13LoC storyline to access him or /goto someone. I would also suggest getting a Dragonoid of Hours from Dragonoid at /mqlesson as it disables his Astral Shift ability - this doesn't need to be equipped to work, just in your inventory.
(Necro) Scroll of Dark Arts x4 (stacks to 4)
Defeat Ultra Vordred at /epicvordred (~1% drop rate).
Doom Heart (doesn't stack)
Defeat Ultra Sepulchure at /sepulchurebattle (~0.5% drop rate).
Necromancer Rank 10
This class is needed to complete a quest in Step 2. To get it, merge the below items at Sally's shop in /necrotower then you need to get it to Rank 10 (follow XP section of New Player guide). You could also purchase it for 2k ACs but I don't recommend that.