Pyroconverger

Wondrous Item A pyroconverger is an Izzet-made flamethrower. It carries a risk of malfunction each time you use it.
As an action, you can cause the pyroconverger to project fire in a 10-foot cone. Each creature in that area must make a DC 13 Dexterity saving throw, taking 4d6 fire damage on a failed save, or half as much damage on a successful one.
Each time you use the pyroconverger, roll 1d10 and add the number of times you have used it since your last long rest. If the total is 11 or higher, the pyroconverger malfunctions: you take 4d6 fire damage, and you can't use the pyroconverger again until you finish a long rest. Uncommon (this item requires attunement)