The Doomsday Trigger was a massive equipment built by Ultron and placed under the Sokovian city of Novi Grad in order to cause a cataclysm on Earth and wipe out all form of life.
History
Powering a Meteor
- "The Vibranium core has got a magnetic field, that's what's keeping the rock together."
"If it drops?"
"Right now the impact would kill thousands. Once it gets high enough, global extinction." - ―F.R.I.D.A.Y. and Iron Man[src]
In 2015, Ultron designed the Doomsday Trigger using a bulk of stolen Vibranium as part of his plan to eliminate all life on Earth, following his belief that this would ensure peace in the world as conflicts would no longer be possible. Ultron built and placed the equipment as a huge and complex set of devices and thrusters placed under Novi Grad, the capital city of Sokovia. Ultron planned on activating the Doomsday Trigger, planning to lift Novi Grad into the air before plummeting it down in the fashion of a meteor.
Ultron revealed the Doomsday Trigger to Tony Stark in the beginning of the battle, unveiling the core of the device placed in the Novi Grad Church. Although briefly confronted by Vision, Ultron activated the Trigger, thus causing Novi Grad to slowly ascend. He then deployed his hundreds of Ultron Sentries to keep the Avengers distracted long enough for Novi Grad to elevate in the sky.
The Avengers defend the core
Since the Doomsday Trigger required to be manually activated by Ultron or his sentries to cause the meteor to fall down back on Earth and trigger a cataclysm, the Avengers decided to gather around and prevent the sentries from touching it. Therefore, waves of sentries led by Ultron himself swarmed towards the core of the device in an attempt to activate it. However, the Avengers were constantly able to repel them, thus endangering Ultron's plan.
A Sentry activates the core
With the hordes of sentries receding, Wanda Maximoff was left to guard the core of the Doomsday Trigger, while the Avengers left to help out elsewhere. However, when her brother was killed by Ultron, Maximoff sensed his death and violently exploded her powers around her, destroying the last sentries attacking the core. Enraged, Maximoff left to find Ultron and kill him herself. However, since she was gone, one remaining sentry was able to activate the core, thus causing the meteor to plummet.
In order to avert a complete cataclysm, Stark was able to make his way through the systems of the Doomsday Trigger. Using his suit's unibeam to create a heat shield, he instructed Thor to strike the Doomsday Trigger's core with his lightning, with the resulting energy causing the entire destruction of both the meteor and the device before it could hit Earth.[1]
