Compared to his weight manipulation and wind spell method, the runic engine was truly simple in principle. But that was just from the principal standpoint.
First of all, Damian couldn't make such detailed and complicated parts as gears, perfectly sized pistons, and a flywheel. And all the added parts join it all together. His extreme control over the black fire produced from his hands and the ability to create hundreds of mana hands that worked in sync with his absurd intelligence stats to put the complicated machine together inch by inch.
