Jarenhäg, the Killing Light (5e Equipment)
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Weapon (evening star), rare (major tier) (requires attunement)
Long, long ago, before even the first of the oldest races existed, giants and dragons fought in long, seemingly endless wars of atrition. However, nearing the end, both sides were rather weak. The giants, master craftsmen, sought out a superweapon, something to end the conflict before both sides were destroyed. In a miraculous stroke of luck, deep within the earth they located a strange unknown material in massive veins, and with research, discovered it to be beyond destructive when combined with other materials, a few dozen pounds had the power to turn mountains into flat, dying wastelands.
With haste, they assembled this great superweapon, believed to contain hundreds of thousands of pounds of this unknown material, more than enough to kill every surviving dragon. But, before it could be activated, the Allfather himself spoke to them, demanding it be destroyed. So it was, shattered into innumerable pieces. The giants then lost the war, as the first races begun to appear.
And thus, the Jarenhägs were assembled, but for what purpose is unknown. Possibly as weapons in their own rights, but most giants outright fear them, seeing the presence of one as a very, very bad omen.
The Jarenhäg is a large and powerful mace, made of strange materials. The handle is pure, smooth stone, its entire surface covered in giant script, repeating "The world must die to be reborn". Reinforced adamantine is bolted to the stone and the strange material making up the head, a faded red and black. Not exactly hammered into shape, the material looks much more like a chunk of something, simply just attached.
While not very magical in appearance, when an attuned creature swings the weapon, it's capabilities become obvious. It saps large amounts of the users energy, swinging the weapon significantly harder than humanly possible. However, after a certain point of sapping your strength, you become completely unable to swing it.
Magical. The Jarenhäg counts as magical for the purposes of overcoming resistance and immunity to non-magical damage.
Acceleration. On a hit, the Jarenhäg deals an extra 2d10 Bludgeoning damage. However, every time you make an attack with it, you gain one level of Exhaustion, which you lose at the end of your next turn. You cannot make an attack with this weapon if you have at least two levels of Exhaustion.