Blood Demon is an Epic ability added in Update 6.3. The update log says you morph your own blood into weapons, apply a mark that can drain the target, and pay HP for your own moves. Its line is "I despise geniuses. They lack the beauty of accumulated effort."
Unlock
- Get a Grimoire from a Mimic. Antique Chests can spawn as Mimics at Dragon's Cavern, in front of Dragon's Cavern, the Prison, and near West Park.
- Get Greater Demon Horns from The Deceiver. That fight is Hecate's Slayer Quest. Demon NPCs tied to the quest spawn at Syrup Village and Floating Village.
- Craft a Bloodied Tome from a Grimoire and Greater Demon Horns. Walkthroughs also call this item a Bloody Tome. The update log's name is Bloodied Tome, and the recipe it prints is those two materials.
- Equip Standless.
- Use the tome on Standless.
If you are also doing The Last Great Mage, keep the quest's 3 Grimoires separate from this craft unless you have already turned those 3 in. The Grimoire counter on this site uses 4 as the combined default.
A regular Demon Horn is a different Rare drop from Demon NPCs. It is not the Greater Demon Horns the tome asks for.
How it plays
The update log is the combat contract: pressure with blood weapons, mark the target, and watch your own HP. Walkthroughs add these reported details: moves apply mark stacks, hitting a marked target deals extra damage and heals you based on those stacks, Blood Grasp is a grab, and Blood Ledger is a mode that stores HP costs in a buffer instead of applying them immediately. Named moves that appear in a detailed moveset writeup include Bury, Blood Needles, and Crimson Sink. Damage numbers for those moves were not in the update log.
Choose it over the mage when
Pick Blood Demon if you want the shorter craft and you are comfortable spending HP. Pick The Last Great Mage if you want the longer quest and ranged spells. The update log does not publish a power ranking of the two.