You have a +6 bonus to attack and damage rolls made with this magic weapon. In addition you can add 1d10 of lightning damage to one of your attacks but you need to declare you are doing it before your attack is made.

After reaching a high point in the land and either meditating or holding it aloft you unlock Call Lightning. You use one charges to cast the spell Call Lightning at 3rd level, if you use more then one you cast it at a high level up to level 9 if you do so add 1d10 for each slot level above 3rd.

After reaching low hp (1/4 of you hp left) or you are surrounded you unlock the spell Thunderwave. You use one charge to cast the spell Thunderwave at 1st level, if you use more then one you cast it at a high level up to level 9 if you do so add 1d10 for each slot level above 3rd.

After reaching low hp (1/4 of you hp left) you unlock the spell Thunder Dash. You use one charge to cast the spell Thunder Dash at 3rd level, if you use more then one you cast it at a high level up to level 9 if you do so add 1d10 for each slot level above 3rd.

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

Notes: Bonus: Magic, Damage: Lightning, Damage, Combat, Versatile, Push