Thunderstone Striker (Aka Boom Stick)
Legendary, Two-Handed, Heavy, Thrown (20/60), Requires Attunement

This wood and hammered iron maul is inlaid with a number of yellow gems that faintly pulse with energy. These thunderstones are rare gems that can only be found forming in the stomachs of the even rarer colossal earthwyrm. These stones emit energy directly proportional to the force applied to them, allowing the weapon to weapon to become more powerful the stronger its wielder is.

Magic Weapon. You gain a +2 bonus to attack and damage rolls made with this magical weapon.

Thunder Smasher. Attacks with this magical weapon deal an additional 1d8 thunder damage on a hit.

Here Comes the Boom. This magical weapon has ten charges, and regains 1d4+1 expended charges each day at dawn. If an effect of this weapon requires a saving throw, the DC is equal to 8 + the wielders strength modifier + the wielders proficiency bonus.

Additionally, you gain resistance to thunder damage. Whenever you take ten or more thunder damage, the weapon regains 1d4+1 expended charges.

Once per turn, when you hit a creature with an attack using this weapon, you can expend between one and three charges to deal an additional 1d8 of thunder damage to the target for each charge spent. The target must then make a strength saving throw. On a failed save, they are pushed five feet in a direct line away from you, plus an additional five feet per charge spent.

Proficiency with a Maul allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Bonus: Magic, Resistance: Thunder, Damage: Thunder, Use weapon to kill a colossal Earthwyrm, Damage, Movement, Combat, Heavy, Two-Handed, Topple