The Alliance refers to the alliance formed between the Explorers, the Cygnus Knights, the Resistance and the Heroes formed by Cygnus to prepare for the oncoming threat of the Black Mage. Once the Black Mage had reached the height of his power, the Alliance had expanded to include the Nova race, the Temple Keepers of the Temple of Time and the members of the Sengoku Era to aid in taking down the villain.
The alliance was introduced during the Advance of the Union update.
The Alliance takes action directly several times in events like Black Heaven, also in the quest line in Twilight Perion, where everyone has the same dark dream and Cygnus sends the player to investigate the situation through the Gate to the Future.
After word reaches that they have found the location of the World Tree somewhere in the Root Abyss, the Alliance sends a member to slay Damien's generals which have been keeping her sealed from leaving. After they have been defeated, Alicia is placed in Ereve where she would be kept under surveillance. Despite her safety being put in the hands of the Cygnus Knights, Damien would kill Shinsoo and capturing Alicia again, this time he would personally keep her under his wraps.
Unbeknownst to the Black Mage commander, killing Shinsoo also awoken Cygnus's powers, who revives Shinsoo.
At some point, the Alliance also learns that the Black Mage had recruited a new commander, one who has the ability to manipulate dreams. The Alliance sends a member to investigate the Gate to the Future who reports that in the future, Cygnus had turned evil in pursuit of power and the Resistance started worshipping the Black Mage. This breeds some internal mistrust in the Alliance, but Shinsoo assured them that the future they were told about was just an illusion and made to try to break them apart from the inside. Knowing that this is fake, the leaders of the Alliance dismisses this.
The Alliance soon decodes some cryptic crossword messages in the Daily Edelstein Newspaper with the help of the greatest minds of the Alliance. The message said: "Black Heaven is Ready", which suggested that Gelimer was preparing for for. The Alliance gathers on the Lumiere to bring the fight to Deliver and destroy his new weapon. After a lot of struggle, the Alliance was able to slay both Gelimer and Lotus, two commanders of the Black Mage, as well as destroying the Black Heaven ship with help from an outside source, but at the cost of losing their ace due to a poison trap set by Gelimer. Cygnus, knowing full well the consequences, uses the last Seal Stone to revive their ace, but doing so also removed the last restraint of power from the Black Mage.
With the defeat of Arkarium at the Arcane River, the Alliance sends Ollie, a Thunder Breaker of the Cygnus Knights, Shubert, a demolitions expert of the Resistance, and Melange, a magician from a secret organization in Pantheon, so secret that not even Angelic Buster knew they existed, to assist the ace of the Alliance in retrieving the White Sun in the Origin Sea, to prevent the Black Mage from absorbing Tana's power to become transcendent of both Maple World and Grandis. After defeating Will, the ace must stop the ritual to foil the Black Mage's plan, but doing so requires to kill Tana, which the ace cannot bring themselves to do. They decide that Tana had suffered all her life and that they are determined to save her, but they took too long to make a decision and Will leaves them for dead, and succeeding his mission. Neinheart and the Cygnus Knights however come to the ace's rescue at the last second. Although disappointed with the Black Mage absorbing Tana's powers, Neinheart respects the ace's determination to save Tana, and that now they have to bring the fight to the Black Mage himself.
Knowing that they are no match for the Black Mage at his full strength, the Alliance seeks help from the Nova people, who gladly help as the Black Mage extends to their world and as repayment for retaking Heliseum. The Alliance also seeks help from the Sengoku Warriors, and the Temple Keepers of the Temple of Time assists the Alliance as well.