This has been in operation for a few months now. Basically, every ship, flying, submerged, or floating on the surface within 10 miles of SD is tracked at all times.
We start with
Detect Ship. It's a 3rd level spell that reaches one mile per caster level by default, and while that is a large area, it's not really suitable for our purposes at minimum caster level. Instead, we Enlarge it and rather than use the minimum 7th caster level for the resulting 4th level spell, we instead enchant it at 10th caster level. That raises the radius to 10 miles from the point of origin, which is much more reasonable and falls within the abilities of our hired Master Enchanters (who are all 10th level). A constant 4th level spell effect at 10th caster level will cost us 6,000 IM after taking into account the discount for the base effect having a duration 24 hours and the +50% tax for adding an additional effect to an already existing item.
Then we tie a basic
Track Ship effect in with the Detect Ship function. This one allows us to catalog our ships, along with all ships which make port in Sorcerer's Deep, making note of their names, captains, and other relevant information. We can also assign each of them an Imperial Registration Number for ease of reference. Adding this as a constant effect to the system will cost 1,800 IM after taking into account the +50% tax for adding an additional effect to an already existing item. A separate Track Ship system tied to a large nautical chart (or a globe after we get a good orbital view of Planetos) would be used to track ships that move beyond the 20 mile Detect Ship effect.
And tying it all together would be a
Mirage Arcana spell at 10th caster level. The Mirage Arcana effect would generate a massive holographic illusion within the tracking chamber using the spell's ten 20-foot cubes to show a scaled down image of Sorcerer's Deep and the surrounding space for a radius of 10 miles, with every ship under the water, floating atop it, or flying overhead represented by a tiny illusory duplicate. This would cost 10,000 IM.
A central operator would rest in a command and control cradle which would magically feed the output from the Detect Ship spell into their mind, allowing them to be simultaneously aware of all ships operating within range. The cradle would grant the operator a +10 Competence bonus to Profession (Sailor) skill checks in order to maximize the effectiveness of the Detect Ship spell (at a cost of 1,000 IM). The operator would be able to mentally manipulate the Mirage Arcana illusion to zoom in one specific areas, such as the port facilities of Sorcerer's Deep, in order to better view all of the ships docked there. A flock of Calligraphy Wyrms and Imperial assistants could help to catalog the information, updating our records and taking some of the load off the central operator.
The total cost for this system would be 18,800 IM.
It wouldn't be able to track troop movements or ground traffic, but we could probably upgrade it with relative ease to use something like specially placed Dragoneye Runes to track individual fliers (Dragons, Erinyes, Heralds, etc).
