Arcane Explosives

The blast disk is the most common form of magical explosive used in the Five Nations. While blast disks serve a similar role to bombs or landmines, they can produce a wide range of magical effects; a blast disk could trigger a burst of confusion and start a riot, or summon a rampaging elemental into a crowded town square.

All nations employed blast disks during the Last War; when exploring abandoned battlefields, untriggered blast disks are an ongoing threat. While all nations used simple force or fire explosions, there were a few variations tied to specific nations:
• Aundair made extensive use of high-powered blast disks; they were infamous for dragonhawk squads equipped with cloudkill disks.
• Breland utilized the base model of explosive disks.
• Cyre experimented with psychoactive effects—confusion, fear, and explosions that dealt psychic damage.
• During the ascendancy of the Blood of Vol, Karrnath created disks that first dealt negative energy damage, then inflicted effects such as danse macabre—killing victims with the initial explosion then animating the corpses to prey on survivors.
• Thrane developed blast disks that dealt positive energy damage—a useful tool against Karrnathi undead. Toward the end of the war, Thrane was working on dawn disks.

While the basic blast disk is a common magic item, under the Code of Galifar, they’re illegal for civilians to own or carry. House Cannith manufactures blast disks, but won’t sell them to civilians (at least, not openly). So if you’re looking for a blast disk, you’ll need to have criminal connections or build your own.

The following statistics describe the standard rules for blast disks, but more powerful versions can be created to serve the needs of a particular story. A powerful explosive disk could have a radius of hundreds of feet instead of just twenty, while a cloudkill disk could unleash a force that expands as it moves and lingers for hours or days.

Many different forms of artillery and explosives were developed during the war, often abandoned once they proved too expensive or difficult to produce. The above are only a few examples of the magic-empowered tools used during the war.

Blast Disk

Wondrous item, common, uncommon, or rare
A blast disk holds destructive arcane power. A typical blast disk is about nine inches in diameter and one inch thick, made from layers of different metal; dragonshards are embedded in the surface of the disk and arcane symbols are engraved in its surface. Anyone studying the surface of the disk can make an Intelligence (Arcana) check corresponding to the save DC of the disk. On a success, they identify the spell effect contained within the disk.

There are three elements to a blast disk: the trigger, payload, and charge. Each effect is selected at the time it is created.
Trigger. A spellcaster touching a blast disk can use an action to activate it. However, generally you don’t want to be holding a blast disk when it goes off. A blast disk can be created with one of the following triggers, or with a more complex trigger of the creator’s choosing (e.g. to detonate when a certain word is spoken, when a specific object comes within range, etc.):
Time. When the disk is activated, the user can set a time delay of up to 10 minutes before it releases its effect.
Proximity. 30 seconds after the disk is activated, it can trigger when someone comes within a certain distance of the disk or when someone first makes contact with the disk, then breaks that contact.
Impact. The activated disk can be set to detonate on impact, then used by throwing or dropping it.
Payload. When the blast disk is triggered, it produces one of the following magical effects, chosen when it was manufactured:
*Explosive. This creates an explosion in a 20-foot radius centered on the disk. Each creature in the area must make a DC 13 Reflex saving throw, taking 2d10 damage on a failed save, or half as much damage on a successful one. An explosive blast disk deals triple damage to objects or structures. The damage type is set when the disk is created.
*Spell Effect. The disk produces a spell effect when triggered. The effect must target either a single creature—whoever triggers the disk—or an area of effect centered on the disk. The level of the spell in the disk determines the saving throw DC and attack bonus, as well as the item’s rarity, as shown on the Blast Disk Power table.

Charge. A typical blast disk holds a single charge, the dragonshards shattering when the effect is triggered. However, more advanced blast disks recharge at dawn; this increases the rarity of the disk by one category.
Disarming a Disk. When used on the battlefield, blast disks are typically buried or hidden. Finding the disk requires a successful Intelligence (Investigation) check, with a DC equal to the ability check that was used when it was hidden, such as Wisdom (Nature) or Dexterity (Sleight of Hand). To disarm a blast disk, a character with proficiency in Arcana must succeed on a Dexterity check using thieves’ tools, with a DC equal to the save DC of the disk. If the check is failed by 5 or more, the disk detonates as if it were triggered. Successfully disarming a blast disk expends one charge, meaning most blast disks will be rendered inert after disarming.

Arcane Explosives

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