|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 Blackdragvisor.
- 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. While Pryce and Chance imply that all Advent Beasts give their Riders nightmares, Dragblacker is the only instance of an Advent Beast doing so to a Rider they aren't initially Contracted with.
- Unlike Kamen Rider Ryuki, Dragblacker was not killed and shown to be a good Advent Beast.