Touch an object or piece (living or not) of an object that is roughly the size of a softball or as big as ten feet high while muttering the verbal component. The item is now primed. The only sign that the item is primed is a faint golden glow that one must pass a DC 13 Perception check to see. The only way the primed target can know that it has been primed is with any spell that detects magic, unless the point where the target was touched is within eyeshot.
Once primed, the object can be detonated at any point on any creature's turn simply by the caster thinking to do it. Upon triggering it, the object detonates in an explosion that leaves it unscathed, but deals 6d8 magical Bludgeoning damage (half on a successful Dexterity save), to every object within (5 + (Height of object in whole feet x 5)) feet. If a creature is in physical contact with the transmuted bomb, they automatically fail the Dexterity save and take double damage. All objects not nailed down in the explosion's range, if not incinerated from the blast, are launched out of its radius and will deal 1d10 (damage type up to DM) to any creature that is in the object's way. All creatures within the explosion radius fall prone unless they beat the caster's spell save DC in a Dexterity check. This spell will harm the caster if they are in its explosive radius.
Once the spell is triggered, the object is no longer primed and the spell ends.The caster can also cancel the spell by touching the target again, though the spell slot is already expended.
The transmuted object can be interacted with as normal when transmuted, even if it is damaged or destroyed. The pieces will no longer be transmuted if the clump of matter falls below the length and width of a softball, however.
* - (A pinch of saltpeter and sulfur.)