5e SRD:Wand of Fireballs
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Wand, rare (requires attunement by a spellcaster)
This wand has 7 charges. While holding it, you can use an action to expend 1 or more of its charges to cast the fireball spell (save DC 15) from it. For 1 charge, you cast the 3rd level version of the spell. You can increase the spell slot level by one for each additional charge you expend.