Brightest Day

In the 2010 - 2011 Brightest Day miniseries, Ronnie, still clad in casual clothing from a wild party the night before, arrives at Jason's apartment with Professor Stein and Ray Palmer to attend Gehenna's funeral. Stein and Palmer discuss Ron's return and how he no longer remembers anything since his death at the hands of Shadow Thief. While the two talk about the paperwork needed to have Ronnie's legal status as "dead" reversed, Ron approaches Jason and offers an apology about Gehenna's murder. Jason refuses to accept it, telling Ronnie that he forced him into being an accomplice to the death of his girlfriend, and that he probably doesn't even remember her name. When Ronnie is actually unable to remember Gehenna's name, Jason angrily lashes out and punches him in the face. This causes the two young men to merge into Firestorm, and they begin arguing inside the Matrix while Palmer transforms into his Atom persona in order to help them separate.

Palmer manages to separate Jason and Ronnie, but not before the Firestorm matrix causes a huge explosion, transmutating everything in the Professor's laboratory into table salt. While recovering in the hospital, Stein explains to Ronnie that it seems to be very dangerous to fuse into Firestorm again. Also, it is revealed that Ronnie, after quickly leaving the hospital and being threatened by Jason's father to stay away from Jason, lied to everyone, as he seems to perfectly remember murdering Gehenna as a Black Lantern.

Some time after the forceful separation, he lies sleeping in preparation of a party, when a previously heard voice prods him awake - a monstrous construct of Gehenna, made totally of salt, which proceeds to throttle and choke him, taunting him to remember her name; while she is interrupted before killing him, Ronnie is left covered in salt. Not too long after, he is lying, recovering from a massive binge, when Jason again forces the merge to help several construction workers endangered when the girders at the site are transmuted without warning to bubble gum. This time, they again hear the mysterious voice taunting them, and Ronnie accepts he remembers killing Gehenna, and they realize something else is lurking from within the Firestorm Matrix.

As Firestorm, Ronnie and Jason visit Stein in an attempt to find out what is happening to them. Stein reveals to them that the Black Lantern Firestorm still exists in the Firestorm Matrix. Firestorm is then told by the Entity that they must learn from each other and defeat the Black Lantern Firestorm, before he destroys the Entity. Somehow, Jason and Ronnie trade places.

After running a test, Professor Stein reveals the origin of the Firestorm Matrix. Stein believes that during the initial experiment he was able to capture the spark that preceded the Big Bang that created our universe. Thereby making the matrix a trigger for a new big bang, if the boys continue to experience emotional imbalance, they increase the likelihood of triggering a new big bang. After explaining this to the boys, the voice inside them speaks again. Declaring that it is not the matrix, a pair of black hands reaches out from inside Firestorm. Forcibly separating Jason and Ronnie, Black Lantern Firestorm stands between them, separate from both Ronnie and Jason and apparently calling itself "Deathstorm".

Deathstorm reveals its plan to Stein, stating that it intends to create enough emotional instability between Ronnie and Jason that the Matrix will trigger another Big Bang thereby destroying of all life in the universe. In order to help accomplish this goal, Deathstorm absorbs Stein's mind in order to use his knowledge of Ronnie against him; then, to torture Jason, Deathstorm brings his father, Alvin Rusch, to the lab and absorbs him as well. Taking flight Deathstorm beckons Ronnie and Jason (who by now have merged into Firestorm) to follow it. Deathstorm leads them to Silver City, New Mexico and the resting place of the Central Power White Lantern Battery. Deathstorm tries to lift the battery but is unable to until he infects it with black energy, after which he is able to lift it with ease. After he threatens to destroy the White Lantern Battery and therefore prevent Ronnie and Jason to truly live, a voice beckons him not to. The voice, commands him to bring the Central Power White Lantern Battery to the voice as well as an army, at which point Deathstorm brings back the Black Lantern versions of Professor Zoom, Maxwell Lord, Hawk, Jade, Captain Boomerang, Martian Manhunter, Aquaman, Hawkman, Hawkgirl, Deadman and Osiris.

Deathstorm and the Black Lanterns teleport to an unknown location, Firestorm, Jason and Ronnie ultimately seek the help from the Justice League. Firestorm arrive at the Hall of Justice asking for help.[27] Firestorm is placed in a containment chamber while the League search for a way to stabilize the energy. However, an internal argument between Ronnie and Jason ignites the spark, apparently resulting in the destruction of the universe. Ronnie and Jason quickly notice, after defeating an hive of Shadow Demons, that the universe was not destroyed as they thought but they were actually transported to the Anti-Matter Universe. There they are contacted by the Entity who reveals to them that since Boston Brand has not yet found the one who will take the Entity's place, it is Firestorm mission to protect the Entity. Meanwhile, Deathstorm and the Black Lanterns are shown on Qward delivering the White Battery to someone. That someone is revealed to be the Anti-Monitor, who seeks to harvest the life energy within the Lantern to grow stronger. Firestorm takes the White Lantern and attempts to fight the Anti-Monitor, but is defeated. Deathstorm then brings Professor Stein out of his Matrix to taunt the two with. Deathstorm then attempts to turn Ronnie to salt, but the Professor takes the brunt of the attack. Angered, Ronnie decides to truly work together with Jason to avenge the Professor. The Entity then declares that Ronnie has accomplished his mission, returning life to him in a burst of white energy that obliterates the Black Lanterns, returns Jason's father to his home, and deposits Firestorm in the Star City forest. Ronnie angrily attempts to make the Entity resurrect the Professor, but is refused. Deadman then arrives, demanding that he be given the White Lantern.

When the "Dark Avatar", made his presence known, Firestorm is part of the Elementals. Ronnie Raymond was then transformed by the Entity to become the element of fire and protect the Star City Forest from the "Dark Avatar" which appears to be the Black Lantern version of the Swamp Thing. The Elementals are then fused with the body of Alec Holland in order for him to be transformed by the Entity into the new Swamp Thing and battle against the Dark Avatar. After the Dark Avatar is defeated, Swamp Thing brought back Firestorm to normal. Afterward, Ronnie and Jason must find a way to contain their Firestorm matrix from the explosion less than ninety days.