Wondrous Item

Varies Some Properties Require Attunement by a Spellcaster Requires Attunement

Mythallars are polished crystal devices with an ellipsoid or spherical shape. By capturing ambient magical energy from the Weave and breaking it down into raw magic for storage, a mythallar can serve as an energy source for powerful enchantments.

“Small” mythallars have a diameter of 25 feet and weigh 500 pounds, but mythallars created for Netheril’s floating cities were roughly 150 feet in diameter and weighing up to 50 tons. For every 500 pounds of weight, a mythallar can be attuned to by one creature; otherwise, mythallars follow the attunement rules in the Dungeon Master’s Guide. If the maximum number of attuned users is reached and another creature tries to attune to a mythallar, nothing happens for that creature.

Additionally, for every 100 pounds of its weight, a mythallar can store 2 charges (or 20 charges per ton). The mythallar regenerates 1 charge for every 200 pounds of its weight per day at dawn (or 10 charges per ton). Other properties of the mythallar continue to function, even if you expend its last charge.

All mythallars have the following properties:

Create Lesser Mythal (requires attunement).

When a mythallar is partially or entirely within the area of a high magic field and you cast a spell with a duration of 1 hour or longer within the field, you can use your reaction and expend one spell slot equal to the triggering spell’s level to store the spell in the mythallar. For the duration of the spell’s casting time, the mythallar must be at least partially within your high magic field or the spell fails.

When the spell’s duration ends, if the mythallar has enough charges available, it automatically expends a number of charges equal to the spell’s level and extends the spell’s effects by its original duration. Otherwise, the spell ends. Spells don’t require concentration or material components when extended in this manner.

All attuned users are aware of lesser mythals attached to a mythallar, and any attuned user can control (or end) these spells while they are within 30 feet of the mythallar. A spell that has been ended is erased from the mythallar and can’t be restarted.

Quick Charge (requires attunement).

As an action, you can cause one magic item you’re holding within 30 feet of the mythallar to expend any number of the mythallar’s charges to regain an equal number of the magic item’s charges or uses, up to its maximum. A magic item recharged in this manner can’t be recharged by the mythallar again until after the item regains all expended charges or uses through its usual means.

High Magic Power Source (requires attunement).

When a mythallar is partially or entirely within the area of your high magic field, you can use the mythallar as a conduit for channeling raw magic energy instead of your own body. Once per round, you can cast one incantation using charges from the mythallar as if they were your own spell slots. Each charge is equivalent to one slot level, and you can use a maximum number of charges equal to your spellcasting ability modifier per round (minimum 1). For example, a wizard with an Intelligence score of 16 (+3) can use 3 charges per round, providing the equivalent of a 3rd-level spell slot. Additionally, when a spellcaster uses the mythallar in this way, the Spellcraft check for casting this incantation is made with advantage.

Quasimagical Energy Source.

A mythallar can function as a power source for “quasimagical” items within a range of 1/16 mile (roughly 330 feet) per ton of weight (e.g., 31/8 miles for a 50-ton mythallar). Quasimagical items can use roughly the same degree of power as common magic items, but they are non-functional outside the range of the mythallar. Quasimagical items don’t consume the mythallar’s charges.

Mythallars were often enchanted with additional unique properties, such as warding spells to protect the city or stronghold where they were housed. (The Ythryn mythallar, for instance, allowed an attuned user to cast a high-magic-enhanced version of the control weather spell.)

Touching a Mythallar.

Any creature that touches the globe of the mythallar must make a DC 22 Constitution saving throw, taking 180 (20d10 + 70) radiant damage on a failed save, or half as much damage on a successful one. Undead have disadvantage on this saving throw. Any object that touches the globe, other than an artifact or the mythallar’s cradle, is disintegrated instantly.