This is a boss class creature.  So far It's being called the Poison Flame Drake.  It gets it's name from the violet flame it emits which does little incendiary damage compared to normal flames, but instead inflicts a life draining poison through the singed skin.  It produces this flame by spitting flammable gasses from an opening in it's throat and snicking the tips of it's tongue together to create a spark.  It also has a powerful tail, bite, and set of claws.  An average sized person would be a bit taller than it's shoulder.

I've been messing around with perspective a bit lately.  This is a study in two point I did.  It's a dark sci-fi city.  Building it absorbed all the planets resources, so anyone outside the city lives poor lives, not to mention the wildlife which is mostly extinct.  Since there isn't anywhere else to live the buildings have to keep getting taller to keep up with the population and eventually a stabilizing mechanism was created that allowed building parts to float to keep from falling over.

This is a medieval wagon designed to help in scaling walls of fortified castles and such.  It's rather big so it's being pulled by two large creatures, but a team of horses could replace them or a company of soldiers with a few design tweaks.  It has a compartment that can fit a group of men so they don't have to worry about getting shot by an arrow on the way to the wall at least.  The carrier creatures are heavily armored with slabs of iron so they are well protected, and when the wagon is parked next to the wall they are either released or simply aren't of any concern as now the defending soldiers have men climbing the ladders to contend with.  Furthermore the wagon can drive along the wall to drop men off at lesser guarded spots.