|This article is about a/an Mirror Monster in Kamen Rider: Dragon Knight.|
Like Dragon Knight, Onyx slots his Cards on the dragon-like slot on his left arm called the Black Drag Visor.
- Attack Vent: Summons Dragblacker to directly attack his opponents.
- Sword Vent: Conjures a black dragon-designed broadsword.
- Strike Vent: Attaches a black dragon-like gauntlet on his right hand to shoot a burst of black flames assisted by Dragblacker.
- Guard Vent: Attaches black dragon-like guards on his arms.
- Final Vent: Summons Dragblacker for Onyx's Final Vent. Onyx jumps into the air while Dragblacker emits dark energy that paralyzes the opponent's legs, then he delivers a flying side kick with Dragblacker flying behind to boost the attack's power with its dark flame.
- Link Vent: Unites and unleashes the power of all of 13 Final Vents.
Dragblacker seemingly has the ability to interact with Riders through their dreams when their stress is palpable; manifesting a specter of its patron Rider in Kit Taylor's nightmares. The full nature of this ability, as well as whether it is unique to Dragblacker remains unknown.
- Unlike Kamen Rider Ryuki, Dragblacker was not killed and shown to be a good Advent Beast.