Arcane Cannon

Arcane Cannons are magical devices designed to fire powerful rounds of elemental magic.

Description
Arcane cannons are large apparatuses that require no ammunition, but rather are powered by magic.

The cannon found in Halas's lair is made of an ivory colored wood that lacks the normal patterns one would expect from that material. It is noted to have similar glowing elements to the strange machinery in Gelidon's lair. On top of the cannons are a few levers used for aiming; a small chair for the operator to sit, and five buttons with odd symbols that glow deep green, red, light blue, intense blue, and dull green.

The cannons on the Wind of Aeons have brass elements, appear to be of elven construction, and are inscribed with arcane runes.

Features
It takes one action to aim the cannon, and one action to fire it, after which it must recharge for five minutes before it can be fired again. The cannons found in The Folding Halls of Halas do not need this same period to recharge, as they are fed by massive amounts of arcane energy through the floor they are mounted to.

Rounds

 * Acid Jet: Fired by pressing the deep green button. The cannon shoots a line of acid that is 300 feet long and 5 feet wide. Each creature in the line must make a DC 15 Dexterity saving throw, taking 22 (4d10) acid damage on a failed save, or half as much on a success. A creature that fails the save also takes 11 (2d10) acid damage at the start of each of its turns. The creature can use an action to wash the acid off with a pint or more of water.
 * Fire Jet: Fired by pressing the red button. The cannon shoots a line of fire that is 300 feet long and 5 feet wide. Each creature in the line must make a DC 15 Dexterity saving throw, taking 33 (6d10) fire damage on a failed save, or half as much on a success. Flammable objects in the line are also ignited.
 * Frost Shot: Fired by pressing the light blue button. The cannon shoots a ball of frost to a point up to 1,200 feet away. Each creature in a 30-foot-radius sphere centered on that point must make a DC 15 Constitution saving throw, taking 22 (4d10) cold damage on a failed save, or half as much on a success. Creatures that fail the save also have their speed reduced by 10 feet for 1 minute. The creature can repeat the save at the end of its turn, ending the slowness on a success.
 * Lightning Shot: Fired by pressing the intense blue button. The cannon shoots a ball of lightning to a point up to 1,200 feet away. Each creature in a 20-foot-radius sphere centered on that point must make a DC 15 Dexterity saving throw, taking 33 (6d10) lightning damage on a failed save, or half as much on a success. Creatures wearing metal armor have disadvantage on the saving throw.
 * Poison Spray: Fired by pressing the dull green button. The cannon expels poisonous gas in a 60-foot cone. Each creature in the cone must make a DC 15 Constitution saving throw, taking 22 (4d10) poison damage on a failed save, or half as much on a success. Creatures that fail the save are also poisoned for 1 minute. The creature can repeat the save at the end of its turn, ending the poisoned condition on a success.

History
In addition to the cannons found in the Folding Halls of Halas, the Cerberus Assembly ship the Wind of Aeons is outfitted with arcane cannons. However, they are not fired onstream and it is possible they do not share the same properties, although they are indicated to be imbued with runes from the school of evocation.