Mechanical dwarven train

Actions

Bullet barrage: The train releases a barrage of metal bullets at targets in a 10 foot cone. Targets must make a DC 15 dexterity saves or take 1d100 damage. Targets who succeed take a quarter of the damage. (Must reload as an action)   Flame thrower: The train releases fire at the targets. Targets must make a DC 16 saving throw or take 10d8 damage. Targets who succeed take half damage.   Charge: As a last resort attack the train will ram. +5 to hit (20d6). After this attack, the train explodes. 

This train of absolute destruction was a war machine made by the dwarves in the great human annihilation war. Originally, there was hundreds of these deadly creations that ravaged what is now the ruins. Will great flight mobility, rapid fire projectiles, and burning hot flame thrower barrels, it is could destroy an entire platoon of human guards with no effort. It has a magic crystal hidden in one of the compartments that powers it, and when directly touched by living, sentient organic material, the train follows all commands. The crystal has a AC of 17 and HP of 1.

The MDT, or the last one, resides in the ruins eternally doing its last command, which was to kill on sight. As they were all presumed destroyed, no other commands were given to it.