Necromancer's Lantern (Patreon)

Wondrous item, rare (requires attunement by a warlock or wizard)

While holding this grisly lantern, you can use a bonus action to speak its first command word. The lantern then springs alight, shedding bright light in a 30-foot radius and dim light for an additional 30 feet; the light is a sickly green. Speaking the command word again using a bonus action extinguishes the lantern.

Whenever a Small or larger living creature dies within the lantern's light, it gains 1 charge, up to a maximum of 4 charges. While holding the lantern, you can speak its second command word using an action to expend 1 or more of its charges. For each expended charge, a skeleton appears in an unoccupied space of your choice within the lantern's bright light. The summoned skeletons are friendly to you and your companions. Roll initiative for the summoned skeletons as a group, which have their own turns. They obey any verbal commands that you issue to them (no action required by you). If you don't issue any commands to them, they defend themselves from hostile creatures, but otherwise take no actions. A skeleton remains for 1 hour or until it drops to 0 hit points, at which point it turns to dust. While a skeleton is friendly to you, it has advantage on saving throws against any effect that turns undead. If a skeleton is ever not within the lantern's light, it becomes hostile for the remainder of the duration, even if it later enters the lantern's light again.

The lantern can control up to four skeletons at a time in this way. It can summon up to a total of eight skeletons each day between dusks.

One skull, two skull, three an' four,

Send them out to gather more.

Five skull, six, then se'en, eight,

Shine the light, control their fate!