Depot

Depot (鉄道駅 Tetsudou-eki) is an emitter quirk used by Kumokyo Ichishi.

Description
When used, Kumokyo’s quirk opens a dimensional portal large enough to allow a Class 92 Freight train to exit the rift at speed in a single direction. The train acts as an unstoppable force for the first three seconds after it exits the portal but possesses no special properties afterwards. The train itself disappears after ten seconds.
 * Unstoppable Force: Nothing can stop a Depot train in the first three seconds of its creation. If two Depot trains collide, they go through each other. Such is the strength of the Depot train that it is theorised not even All Might could block a train if they met head-on. Quirks that affect raw objects, such as Cinder, continually affect an invincible Depot train until it is no longer invincible (for example, an exploding but invulnerable Depot train will continue exploding with no damage to itself until three seconds have passed.)

At any point after it leaves the portal, the train is still a physical object, meaning it can be moved by other quirks provided the relative direction and speed the train moves in does not change. It moves at a speed of 90km/h in a straight line dictated by which direction the rift it originates from, and it cannot deviate from this speed or direction during the three second "unstoppable force" period.
 * Immovable Object: Nothing can move a Depot train from its position in the first three seconds of its creation, unless the movement of the train is technically the movement of the space it occupies, not the object itself. For example, Warp can still move the train, as it has technically not changed speed or direction.

Depot's ability is not to create a train - it merely opens a dimensional rift from which a train appears from. The train is always the same and always disappears after roughly ten seconds, suggesting that the train somehow returns to the dimension it is pulled from. The train is also returned in pristine condition, which suggests the train is repaired after it is pulled back, or a different train is used every time. Kumokyo does not use Depot if there is no space to do so without putting herself or her friends in danger, such as in enclosed spaces.

While the train is an unstoppable force during its three-second invulnerability period, it will resist all attempts to deviate it from the single velocity it travels on. It will push aside any object or person, crush barriers, batter through other quirks, and burrow through the earth itself if it needs to. The train in this state is not affected by gravity. After the three-second period, however, the train becomes a mundane object travelling at a speed of 90 km/s, and can be moved or destroyed like a normal train. After ten seconds, the train itself starts to dematerialise, starting from the front and ending at the back. Kumokyo is able to force a train to disappear early, allowing her to control exactly how much destruction she would like one train to cause.

Opening the rift apparently takes a great deal of effort and concentration, and Kumokyo has only ever been able to open one rift by her own efforts before becoming exhausted and collapsing.

Kumokyo's quirk is often used by the Organisation as their ultimate "glass cannon" trump card, seeing as Kumokyo's depot train has to date been totally unstoppable and capable of annihilating anything in the way, at the cost of putting Kumokyo out of commission for the rest of the mission. When she inevitably knocks herself out, Shojirou or Aoki carries her around for the rest of the day.

Usage
Since the Depot Train is physically unstoppable when newly created, Kumokyo is able to use it destructively with extreme efficiency against any tier of obstacle. Kumokyo has to date used Depot to:
 * Destroy a sizeable section of staircase inside the Clearview Bank
 * Attack and kill Queen Bee
 * Destroy a sizeable section of the eastern Japan sea wall, thus flooding the entire underground complex of Queen Bee's secret laboratory
 * Attack and kill Raiden
 * Destroy the THEIA IV supercomputer structure
 * Destroy a large portion of the underground bunker that housed the THEIA IV supercomputer
 * Attack and incapacitate Sariel