Mirakuru (ミラクル, translated as The Miracle) is a serum tested on several criminals by Sebastian Blood's organization.
Its exact properties and intended purpose are unclear, though so far every individual seen to have been injected with the serum has suffered convulsions and begun bleeding from the eyes immediately after injection. The user then enters into a state of near-death, having their heart beat at a practically non-existent level. If the user survives, he/she awakens after a few hours with the serum in full effect, gaining strength, endurance, durability, reflexes, and speed increased to superhuman levels; in addition, to a healing factor. In order for the serum to have the desired effect, a strong sedative must be administered along with it, otherwise the recipient is likely to die. However, it appears that a person's inherent anger can allow them to survive the Mirakuru injection without the sedative, as demonstrated with Slade Wilson and Roy Harper. Human blood is also apparently a component required to either manufacture the serum or to use it properly.
According to Sara Lance, the serum has serious side effects even on those who survive injection, either deforming their bodies or warping their minds. Although, a person can keep themselves from completely losing their minds by focusing on a person they truly care about as shown in Roy Harper's case in his feelings for Thea. Although, he still had violent outbursts, he was able to control himself much better than Slade Wilson, who lost Shado, someone he deeply cared for.
According to Anthony Ivo in "Keep Your Enemies Closer", the Mirakuru was a serum that caused increased strength and rapid cell regeneration created by the Japanese during World War II in hopes of creating an army of super soldiers. They transported their only supply through submarine, and when it was under heavy fire by the Allied Forces, it ran aground on Lian Yu. After the men of Ivo invade the island, they were slaughtered by Oliver, Shado and Slade. Because the picture they have, he managed to set the cave seeking. In the cave, they found a number of bodies of Japanese World War II, all with deformed skulls. Next to the body was a Hozen with scriptures. Some time later, Oliver was kidnapped by Ivo, and forced to take him to the Hozen. After an ambush, Oliver and Sara are rescued by both, and they discover a series of coordinated proceedings of the stone. When they reached the abandoned submarine, he found a box with several injections containing Mirakuru, amid so they inject in Slade, who was dying, due to previous injury, even without the necessary anesthetic. After Slade apparently dying, the men of Ivo, find the submarine and collect the serum, as well as lead Oliver, Sara, and Shado as hostages. Hours later, Slade awakens, his wounds healed completely, and with all-powerful abilities. After running up to Oliver and others, Slade uses his abilities to kill all of Ivo's men.
Sometime later, Ivo tested the serum in several men, however all died. Oliver also managed to recover the remaining samples, and burned.
In "Crucible", Xavier Reed is captured by Blood and injected with Mirakuru; he dies after bleeding from his eyes, unable to control or resist the affects. Also, Sin's friend, Max Stanton was found in an alley, dead with blood running out of his eyes, revealing that he was injected with the serum, but was unsuccessful and died.
In "The Scientist", Gold is shown to have super strength and superhuman durability, as implied by the drug's assumed effects. Furthermore, while he defeats Oliver twice, Oliver claims he has beat at least one user of Mirakuru on Lian Yu. He also states that all of Ivo's test subjects are dead, and that he burned the rest of the serum that they found on the Japanese submarine.
In "Three Ghosts", it is shown that Sebastian Blood recreated Mirakuru using samples from Slade Wilson's blood. Also, Brother Blood forcefully injects Roy Harper with the serum, causing his eyes to bleed until he dies. Oliver though is convinced by a hallucination of Tommy Merlyn to keep fighting and he manages to kill Gold by blowing up the centrifuge, spilling chemicals all over him. Oliver then manages to revive Roy. Later, while resting, Roy discovers that the wound on his knee from where Arrow shot him is completely healed.
In "The Promise", Sara and Oliver burn the box that the Mirakuru belonged in, believing the Mirakuru to be inside it, it is later revealed that Slade hid it, and kept it on him incase he needed it.
- Cyrus Gold (successful; deceased)
- Xavier Reed (unsuccessful; deceased)
- Slade Wilson (used to heal injuries; successful)
- Roy Harper (unwillingly; successful)
- Max Stanton (unsuccessful; deceased)
- Japanese Soldiers (successful; all deceased)
- Deathstroke in the comics was injected with a experimental serum by the US government which left him in a coma for months. When he awoke the serum had enhanced his body giving him the strength of ten men along with heightened speed, agility, stamina, and reflexes. It also increased his capacity to use up to 90% of his brain at any one time. The serum also provided him with a healing factor in his blood that enabled him to heal from physical injury much faster than a normal person; however, it did have limitations, as he could not heal his missing eye and cannot regenerate entire limbs.
- Mirakuru is similar to other drugs used in DC comics such as Venom, a steroidal compound used by Bane to enhance his strength. Venom was derived from Miraclo, a serum used by the hero Hourman which lasted only one hour. Another serum used in the comics was Blockbuster, which permanently enhanced Mark Desmond and his brother Roland Desmond into hulk like monsters.
- Mirakuru was created by the Japanese during World War II, hence its common name.
- It seems that Blood wishes to use it to make criminals into "something else", or possibly force them to obey him (hence his statement made to Xavier Reed if he was "ready to serve" before administering him with the drug).