Mace of the Elemental Hunger - D&D5e (Patreon)

Mace, rare (Requires attunement)

At first sight, this mace appears to be made of stained glass, but you are mistaken if you think of it as a fragile weapon. It is built with a material as strong as diamond and is especially susceptible to elemental magic. You gain a +2 bonus to attack and damage rolls made with this magic mace.

This magic weapon is enchanted to be able to absorb elemental damage. Once a day, when you are affected by acid, cold, fire, or lightning damage you can use a reaction to reduce 1d6 from that damage allowing the mace to absorb the elemental energy. After that, for 1 hour, every time you hit a creature with this magic mace, the creature takes 1d6 extra damage from the same elemental type. The weapon also gains an extra special ability that varies accordingly with the element absorbed.

Freezing Strike. When the Mace absorbs cold damage, it allows you to slow your foes' movement. Any creature hit by the mace has its speed reduced by 10ft until the end of your next turn.

Electric Discharge. When affected by lightning damage the mace grants you the ability to disrupt the reactions of your foes. Any creature hit by the mace can't take reactions until the end of your next turn.

Igniting Blast. When the Mace of the Elemental Hunger absorbs fire damage, it grants you the ability to ignite your enemies. Any creature hit by the mace takes an extra 1d6 fire damage at the start of each of its turns. The creature can spend an action to dose the flames, ending this effect.

Corrosive Touch. When the Mace absorbs acid damage, it gives you the ability to corrode and weaken the armor of your enemies. If a creature wearing armor is hit by the mace, its AC is reduced by 2 until the creature takes at least 10 minutes to fix the armor. A creature can’t be affected by this effect more than once in the same encounter.