Gizmobomb

Casting this spell takes the form of you assembling the many intricate parts of a complicated mechanical device (the material component of the spell) while reciting repeated mystical incantations. Upon successfully casting the spell, the assembled mechanical device is armed and can be used by yourself or any other creature in possession of it who knows how a gizmobomb works.

Any creature that knows this spell knows how a gizmobomb works. As an action, a creature that is holding the mechanical device but does not know how a gizmobomb works can succeed on an Intelligence (Arcana) check against DC 15 to learn how it works. If told how it works by someone who knows, the creature gains advantage on this check. If a creature rolls a '1' on their Intelligence (Arcana) check, they activate the device.

The mechanical device has two settings. The first setting is on impact, start of next round, 1 minute, 5 minutes, or 10 minutes for the detonation timing. The second setting is acid, bludgeoning, cold, fire, piercing, or slashing as the damage type. The default settings are on impact and fire. As a bonus action during their turn, a creature in possession of the mechanical device that knows how it works can use both hands to change its settings by manipulating the device's mechanisms, selecting one of the detonation timing options and / or one of the damage type options.

As an action, a creature that has the device in their hand and knows how it works can activate it, and either place the device on a surface within their reach or throw it up to 15 feet x their Strength bonus (minimum 1). A device that has been activated will explode per the selected timing, dealing 6d8 damage of the selected damage type to all creatures and objects in a 10 foot radius sphere. Creatures in the affected area can make a Dexterity saving throw, taking half damage on success. The mechanical device is consumed upon explosion.

If the mechanical device is unattended, a creature encountering the device can pick it up if it is visibile to them, within their reach, and they have a hand free. If a creature has the mechanical device in their hand, and the device is activated but has not yet exploded, as an action they can deactivate the device if they know how it works. If deactivated, the mechanical device will not explode and can be used again later.

The mechanical device retains its magic until it explodes, unless it is destroyed or the spell is dispelled. However, the device gains a cumulative 1% chance that it will fail to explode after being activated for each month that has passed since you cast the spell, to a maximum of 90%. While the spell lasts, the mechanical device has a faint aura of evocation and transmutation magic.

At Higher Levels: When you cast this spell using a spell slot of 5th level or higher, for every slot level above 4th either the radius is increased by 5 feet or the damage is increased by 1d8 (your choice at time of casting).