The Odinforce is a powerful, mystical energy used by the Kings of Asgard, most notably Odin, hence its name. It is the source of power of the spear Gungnir wielded by the Kings of Asgard, and the Destroyer, and must be periodically replenished by entering the Odinsleep.
War Against the Dark Elves
Five thousand years ago, the then-king Bor led the armies of Asgard in their struggle against the Dark Elves into their Homeworld of Svartalfheim to secure the Aether, a weapon of infinite destruction. Upon arriving on the Dark World, Bor fired blasts of Odinforce from his spear Gungnir to cut down swaths of Dark Elves.
Jotunheim Invades Earth
Using the Casket of Ancient Winters, the Jotuns sought to take over the other Realms and unleash a new Ice Age. They began with invading Midgard, but fortunately for its inhabitants the Asgardian armies led by Odin pushed back the Jotuns to their home world. During the war, Odin used his signature spear Gungnir to full effect against the Frost Giant hordes.
During Thor's coronation, a squad of Frost Giants infiltrated Odin's Vault. Sensing their presence, Odin activated the Destroyer, which was stored within the Vault itself. The Destroyer armor powered up, summoning the Odinforce and disintegrating the intruders with energy blasts emitted from its head.
After Thor's disobedience and reckless actions on Jotunheim endangered the Nine Realms, Odin stripped Thor of his power and banished him to Midgard. Odin takes Thor's hammer Mjølnir and uses it to channel a burst of Odinforce that broke apart Thor's armor and pushed him into the Bifrost.
After Loki angrily yelled at his adoptive father for not informing him of his true nature, Odin collapsed in shock. Immediately after, Loki called upon some guards that carried him to the bed chamber where he is supposed to stay until his Odinsleep is over, during which Odin would rejuvenate and replenish the Odinforce.
Due to Odin's inability to perform his actions as King of Asgard while in the Odinsleep, Loki was appointed regent, and after numerous subversive acts against his rule by his subjects and Thor's friends, Loki sent the Destroyer down to Earth after Thor. The automaton laid waste to the small town of Puente Antiguo by incinerating everything in sight with its optic blasts. After suffering fatal wounds as a mortal, Thor regains his power and quickly destroys the Destroyer, easily deflecting its blasts with Mjølnir.
After returning to Asgard and learning of the true state of things, Thor tries to stop Loki's plan to destroy Jotunheim. During the subsequent duel, Loki wields Gungnir and fires several Odinforce blasts against his brother.
As part of the S.H.I.E.L.D. Protocol Phase 2, the wreckage of the Destroyer Armor left behind in New Mexico was salvaged and reverse engineered by S.H.I.E.L.D. scientists to create a gun-like weapon of great power that would fire blasts of Odinforce like the automaton it was made from.
Loki's Campaign on Earth
After coming to conquer Earth, Loki was apprehended by Thor and his new allies at S.H.I.E.L.D.. During Loki's escape, he fatally wounded Agent Phil Coulson with a stab through the heart after deceiving both him and Thor. Before succumbing to death, Coulson fired a Destroyer Armor Prototype Gun that was developed as part of Phase 2 from the wreckage of the Destroyer appropriated by S.H.I.E.L.D. The blast of Odinforce was powerful enough to blow Loki several meters back and through a wall.
Return of the Dark Elves
The start of the Convergence and the unearthing of the Aether reactivated a dormant Dark Elf ship carrying the last survivors of their race. During the Dark Elves' attack on Asgard, Odin vanquished the last of the foes alive in the Throne Room after their initial descent.
After the devastating attack and the death of Queen Frigga at the hands of Malekith, the deceased were put on funerary boats and floated to the edge of the Asgardian sea. Before falling off the end, Odin converted his fallen queen into energy using the Odinforce. While the vessel fell into the abyss, the Odinforce rose among the stars.
Attack on Cybertek
During the Battle at Cybertek, S.H.I.E.L.D. Director Nick Fury showed up to help Coulson and his team against John Garrett and his Centipede Soldiers, bringing with him the Destroyer Armor Prototype Gun. Coulson used its concussive blasts to great effect against the Centipede Soldiers.
After the activation of the ancient Kree City, the Kree Vin-Tak came to Earth to investigate the current state of the Inhumans and to eliminate any if found. S.H.I.E.L.D. came into conflict with him after it became clear he was after their teammate Skye. Leo Fitz used the Destroyer Armor Prototype Gun against the Kree while he was fighting against another teammate Bobbi Morse.
After returning to Asgard from his travels in search of answers about the Infinity Stones and the Fall of Asgard, Thor went in search of his father Odin with his brother Loki, who had been masquerading as Odin and secretly ruling Asgard. Having found Odin overlooking a cliff in Norway, he told his sons it was his time to die and for Ragnarök to begin. Odin subsequently dissolved into Odinforce upon his death.