Steam Great Ballista
The Steam Great Balista used the newfound mechanics of the steam engine to turn a winch, which pulled the bowstring back. An arrow was loaded, and the Ballista fired, before the steam winch pulled the bowstring back again. It can be said to be the first Great Ballista in history. All it took was a tank of water(with a close-able lid to pour water into when empty), Sunseeds, a flywheel in a pipe, and some gears.
They fired bolts with tips of iron, and bolts with a chipped-sharp Sunshard inserted in the end. The first could go through an enemy army with easy, with the bolt being made of heavy woods giving it great power even when if shattered after going through the enemy ranks or spinning from a collision on the ground.
The second was used to set fire to grasslands. For despite looking like an opal, it was as strong as an emerald, even if it could be shattered easily with hard sharpened rocks. This made it a viable weapon for penetration purposes at least, though they were used carefully and rarely since they set grass aflame once shattered and cutting into the water in the grass.
They were placed in encampments, and set up on fields, and could easily be taken apart for transport on carts, with only the empty water tanks being particularly cumbersome.
The Creation of the Black Ceramic, and it's use in Lava Stratification
While rare, there are places where lava can be said to have driped down, forming crags. By opening these crags a bit, and putting a wooden pot filled with Sunseed heated water, the newly dripping lava can be made to solidify under high-temperature and high-energy conditions.
Said being the sunseed's energy lighting the boiling water, and sinking into the lava as it makes contact. This makes an extremely crystalline material that can be taken out once a good amount has been produced and crushed to powdered dust.
This dust is then mixed to form clay, molded, and then placed in the same sunseed-heated bath carefully, and has a lid placed over it.
This effectively bakes the clay into a high-grade ceramic capable of withstanding extremely high temperatures. It is even capable of being used to store lava with no heat issues. Which in turn allows the production of more of the clay which becomes ceramics.
This actually let us fill a pot full of lava, with Sunseeds at the bottom, and leave it for 5 days and nights. At the end of that, the lava has stratified into it's composite elements, including red iron that we can use to make more armor and weapons. And the various colored obsidian produced can be used for arrowheads, cutting knives, and crafts.
Modern Section.
The use of lava drops entering the high energy sunseed-boiled water produced ideal conditions to turn mafic lava into a high grade material for ceramics. The combination of iron, highly purified silica, and oxygen derivatives, created basalt that easily aerated the black clay created, and was removed as it was heated by the boiling water and sunseed's heat energy. This effectively removed all the air in the process, leaving what was called Black Ceramic and/or Obsidian Ceramic.
It was basically a combination of heat temperature synthesis, exotic energy deposition, and rapid heating. Long before those terms came to be known to most.
This Black Ceramic was show to be immune to the heat of lava, though very brittle and not prone to simple cracks. Shattering into many fine pieces would be a better description of what happened if you dropped the finished product. However, it's speckled pattern and geometric coloring made it adored by most.
Etroans used it to hold lava for five days and nights with sunseeds inside. The high oxygen content and higher heat triggered a reaction where the sunseeds kept the lava at it's current temperature. The more there were, the longer that temperature could be maintained. The lava sealed itself on the surface that had contact with air, but the rest of the lava stratified as it very slowly cooled. Until eventually, the oxygen level and/or heat was low enough for the reaction to end and the lava to finish cooling. Materials made this way were oxidized, so they even ended up with aluminium and titanium, though they didn't make use of it do to it's difficulty.
This source of iron was used to make many arms and armors, effectively outpacing the enemy's ability to attack. As battles continued, repairs needed to be done, but the Etroan nation and their allies had a near never-ending supply of iron and obsidian to use. Combined with their fortification abilities, this spelled the end for the invasion.