Arcane Shielding

Common upon Remnant vessels and the ships of other magically-able nations, magical shields allow a ship to endure multiple cannon volleys without the usual drawbacks of armour. The spell works similarly to the telepathy spell on a telepack; it is embedded into a device usually kept in the heart of the ship, and summons the shield whenever a unicorn channels magic into it. Generally, any Remnant ship will have multiple unicorns dedicated to the channelling of the shield, though the issue of whether to have them all channelling at once or to have them switch off as each grows exhausted is an open debate and often varies by captain.

The shield does not deflect or vaporize incoming rounds, as doing so would take a gargantuan amount of effort on the part of the unicorn; it would be akin to casting a hundred levitation or immolation spells with each volley. Instead, it simply slows down anything that passes through it. Physical bullets passing through lose speed and fall to the ocean before they reach the ship, and magical rounds collide with the arcane material that makes up the shield. Magic rounds are much more effective against shields than physical bullets. A bullet has little effect on the unicorn channelling the shield, while magic rounds actually chip away the material of the shield itself, requiring that the unicorn expel extra effort to rebuild it.

Peculiarly enough, the channelling unicorn loses more energy when the ship she is defending fires than when it is hit. This is because she has to temporarily dampen areas of the shield for the protected ship's bullets to pass through, and must afterwards build it back up to keep enemy rounds from penetrating with enough speed to do damage. Magical rounds are usually "paired" with the shield generator of the ship they're stored upon, allowing them to pass through with no contest.

As a side effect of the commonness of these shields on Remnant ships, Remnant cannons fire bullets at much higher velocities than those of their counterparts. The extra speed is usually bled off when the bullet flies through the dampened shield, but some captains have been known to expose their ship and use the speed for extra penetration.