Thunderous Warhammer of the Sentinel

Requires attunement.   This hammer comes with 3 charges by default, which recharge each day at dawn. Once per dawn, roll a D4; on a 4, this hammer gains +1 charges. The charges do not stack, and go away if not used before the next dawn.    Whenever you use the attack action, and hit, it is treated as if you casted the thunderclap cantrip as well.   As an action, you may spend a specified number of charges in order to cast one of the following spells:   Thunderwave (1 Charge) Shatter (2 Charges) Thunderstep (3 Charges)   As well, once every charge is used, you may cast these spells using your own vitality as a spellcasting component. As such, when casting a spell, you take damage which is 10x the level of spell you are casting. If this would drop you to 0 HP, then you may cast a spell, but fail two death saving throws immediately, and, if anyone is in melee range, they may use their reaction to provoke an attack of opportunity.