From publisher blurb:
You know it's your destiny!
For some tinkers, their first automaton is not merely a tool, but also their best friend. Together, tinker and Rusty, for that was its name, adventured throughout the land, righting wrongs, defeating slavering demihumans, and looting fantastic treasures from long forgotten ruins featuring both Euclidean and non-Euclidean geometry.
Then they met their first dragon.
The encounter was a debacle. Though brave to the end, for poor Rusty was built by a such a novice that he was effectively mindless, the tinker's first creation and best friend could not prevail over such a creature. Tears in his eyes, the tinker watched in horror as his beloved friend fell before the lizard's onslaught. Nothing went right. Rusty couldn't block. Rusty couldn't dodge. Rusty couldn't do anything that the tinker himself found easy!
Escaping with what scraps of his beloved companion he could, the tinker immediately set to work on a new and improved Rusty. Bigger to take punishment, stronger to deliver it, the new Rusty was a marvel of engineering; however, despite his best efforts, a larger Rusty was not better at blocking and dodging, for a larger Rusty was not a smarter Rusty. Still, the automaton was impressive. Indeed, such a hulking machine could easily swallow its creator whole.
Or carry it.
After a few simple modifications, the world's first Super Mega Ultra Mecha made headlines by making suplexing a dragon its first order of business.
When it comes to going big or going home, the mechgineer and his Super Mega Ultra Mecha take first prize. Inspired by giant robot cartoons and the power of friendship, this prestige class for the tinker base class believes that every threat that can't be destroyed by excessive electrocution or unnecessary amounts of alchemical firepower can simply be punched into the stratosphere.
Whereas a standard tinker commands squadrons of small automatons, the mechgineer only ever has a single megadroid or gigadroid and his alpha out at any one time. Experienced mechgineers go further, combining their two deployed automatons to produce a Super Mega Ultra Mecha, a massive automaton that bristles with the weaponry of over three standard automatons. Once combined, this Super Mega Ultra Mecha gains access to a number of Super Mega Ultra Subroutines, as well as the mechgineer's Epiphany, a powerful capstone ability selected from a list of offensive and defensive options.
Together, the mechgineer and his best friend are an unstoppable force anywhere the ceilings are at least fifteen feet high.