A kings ransom the alchemist asks, almost all of it the best poured brass. I could shod the axles of a hundred war chariots with what he has asked for. He has asked for a single wagon, or great size and three axles, to be pulled by 12 oxen, and attended by stonecutters, labor-bound ogres, and wagons to carry barrels of his strange alchemist's powder. He has gained what he as requested. If his grand basilisk fails to turn our foes to stone, then he shall spend the rest of his days in a gaol to ponder the folly of his boasts and scope of his demands.
Dondraconuils' Grand Basilisk
In an age of mongonels and trebuchets, King Dondraconuils has financed and constructed a great and mighty siege weapon. The Grand Basilisk is a two ton brass cannon some 10 paces in length and with a bore large enough a stout pig could be greased and packed into the barrel. The barrel is covered with baroque flourishes and artistic renderings of basilisks twinned down the length. The firing port is shaped to look like the jaws of a hungry dragon. The entire weapon is carried on a large wagon with three axles.
When the cannon is used, it is lowered to the ground, with the large rear axle of the carriage acting as the firing support. The weapon is packed with Alchemist's Firedust and the barrel is packed with a stone projectile weighing as much as 160 pounds. The cannon is not very accurate, and shooting a moderate arcing trajectory, aiming is mostly guesswork. After the cannon is fired, the 10 span barrel must be swabbed clean of ash before it can be repacked with fresh firedust. After the barrel is cleaned and packed, a stone cut specifically for the basilisk is greased and packed down the barrel.
Using expert stone cutters and enslaved ogres, reloading the Basilisk can be done in about half an hour.
Thorinsford fell in a day, three stones lobbed through the wall and two misses were enough to unnerve the guard. The ogres were greasing the sixth shot when the courier came, Thorinsford surrendered so long as the demon engine was silent.
Forgevale took two shots and opened the gates. A lucky shot had put the stone round straight through the lord general's tower and had killed half of the nobles gathered there.
Point Sisole surrendered after loosing a cavalry skirmish and sighting the monster basilisk being moved into position.
City after city, tower and trade towns alike, were surrendering. One cannot argue with the Basilisk, one cannot fight the thunder and flame and the destruction that rains down from above.
A Terror Weapon
The Grand Basilisk is not an efficient weapon, nor is it accurate. Maintenance of the cannon is laborsome, cutting the stone rounds for it is time consuming. Carrying the shot is burdensome considering the size and weight of each projectile. The powder required to fire the weapon is also expensive and space consuming. For the cost of the Basilisk, the King could arm, armor, and mount 150 knights in full plate armor and heavy warhorses.
Moving the weapon requires its own specially made cart, which in turn is pulled by one dozen oxen. A second wagon is required to carry the barrels of Firedust needed to use the weapon, and while it only needs 4 or 6 oxen, its contents are flammable and explosive. A second wagon generally carries the stonecutters, their tools, and round or two of shot plus a few pieces still being shaped.
All of this is large, cumbersome, slow moving, and requiring constant protection when on the move, when deployed and when firing. Thus, the cost of the basilisk, and its movement and protection, the king could afford another small army.
All of this aside, the appearance of another army of conscripts and peasant levies do not evoke the same terror as the appearance of the Basilisk. The thunder of the weapon being discharged is enough to cause hearing loss in most of the weapon's crew. The effect of solid stone shot penetrating walls, shattering small towers, and bursting wooden gates is enough to breach heavy defences. The psychological effect is also equally impressive. The debris from such a hit is deadly, and the chances of surviving even a glancing hit are low. Accuracy be damned, it only takes one lucky shot and the defences are broken and the enemy is inside the gate.
Captain Vaele turned his men, a hundred strong troop of horsemen armed with bows and lances and swords. Thorinsford had fallen, Forgevale and Point Sisole had surrendered rather than face the wrath of the basilisk. His company had been turned out, find the weapon and kill its men, burn its wagons, and do what they could to destroy the basilisk itself. They were not the first to try. Others had, and had discovered the weapon protected by archers, swordsmen, and a detachement of Dondraconuils' elite charioteers. The terrain was rough, the chariots would be restricted in movement and the archers would have to shoot through the trees. It was the perfect spot for an ambush.
A few hours later, arrows whined through the air and men and horses were laying about, some dead, some screaming as death came for them. The Basilisk's wagon was damaged and many men were dead, but the ogres had started throwing the barrels of firedust, then the alchemist with them produced some strange implement, a Wand of Lightning Bolts. Such magic was not unknown, but he cast his spells and struck the barrels. Each bloomed with the flame of the basilisk's breath and broke trees and shattered bones. The horses were scattered and lost in the trees, the oxen too were panicked and their harnesses broken.
The Achillies Heel
The Grand Basilisk is a primitive artillery piece. As such, it has many weaknesses, almost any of which can be properly exploited. As mentioned above, the cost of the weapon is restrictive, so no baron or middling mage or city merchant guild will have one. These are the playthings of kings and emperors and they themselves will only have a very small number if they have even more than one. As a psychological weapon, destroying a Grand Basilisk could just as easily demoralize the Basilisk's troops as emboldening the foe.
Maintenance of the weapon is vital. A poorly fit stone, or the incorrect amount of powered could cause a misfire. This could be a simple as a stone lodged in the barrel, or as drastic as a catastrophic failure of the cannon that left the entire crew dead or dazed. The more the basilisk is used, the more the metal of the barrel becomes fatigued and the more likely the barrel will fail when fired.
Finally the ammunition for the weapon is expensive, heavy, and labor intensive. Creating the stone shot requires the proper kind of stone, not just any rock will do. The stone must be stout enough to survive the blast without shattering, but good for shaping otherwise a proper fit in the barrel is impossible. The Firedust used is also labor intensive to create. Bypassing traditional gunpowder and its logical step to basic firearms, firedust is a quasi-magical alchemical compound that burns explosively. This dust takes time to make, and is made a pound or two at a time, rather than in large industrial batches.
Magic can do many of the same things that the Grand Basilisk can do. Many of the spells are cheaper and more reliable than the massive cannon. The disadvantage lies in that every magic spell can be countered. A proper warding can prevent projectiles and rays from reaching their targets, and most such spells require line of sight to work. The Grand Basilisk doesn't have a warding spell that will stop it's massive stone shot. The weapon can also fire an impressive distance, not quite a mile at best range. This allows it to shoot from a distance and hide behind terrain like small hills and such. Plus, there are more mundane answers for mages, such as magehounds, trained to hunt in incapacitate mages, anti-magic effects, and other things as diverse and strange as the magi they counter.
The Chancellor looked at the report. Six cities and large towns pacified. The major trade city of D'erlanger was taken, and the army had repelled two attempts to retake the city. The cost was impressive though. Many soldiers remained alive, which meant they had to be paid. The cost of the maintenance of the Basilisk was starting to become a pain. He growled and tugged his beard. The King had his plaything, and he had annexed the Kilderland, but how long to restore what had been spent taking it.
It was time to put away the Basilisk, and let men remember to fear it. Not to grow complacent with it in sight. Let that gold devouring beast return to its lair and slumber until the king called it forth again.
The Alamo - War is joined and the PCs are caught up in it. The setting is a major siege, and the Grand Basilisk has been roused from it's slumber to rain mountains upon the enemy. The PCs have the option of being part of the Basilisk's guard and can fight of raids and reprisals to destroy the weapon. They can also be the other side, riding out under cover of night to catch the monster unawares and put it to the torch and it's crew to the sword.
A Sound of Thunder - The PCs have been tasked with finding the alchemist and kidnapping him. Their king/benefactor has decided they want a Basilisk of their own, or perhaps the secret of basilisk-proofing their castles. The PCs have to find and capture the man and return with him. Afterwards they can be assigned to finding the components needed to make firedust, secure trade agreements to supply the brass needed for the weapon, and even oversee its construction and eventual use.
The Last Dragon - The Grand Basilisk can be an advent type weapon, heralding a new age of artillery. It could also be a relic of a lost power to be hunted like a very large and heavy dingus. Without means to produce the large cast barrel, the PCs could discover a wonder weapon that is priceless, along with the ammunition to fire it. It could be firedust has been lost, and only a few barrels of the stuff remain in the world. Seems like such a waste, when it takes as many as three barrels of powder to fire the monster.