Giant's Hero Blade

A massive stone blade. Its edges are dull and its weight makes it an impractical weapon. The weapon was crafted for a heroic giant who once wielded the blade to protect his people from a horde of evil dragons. Although the warrior fell during the battle, he managed to slay every last wyrm, keeping his kin safe. The blade functions as a normal greatsword that deals bludgeoning damage instead of slashing damage and with powerful transmutation enchantment that scales the blade's power according to its size. It has a Strength requirement of 18, otherwise, attacks with the blade are made with disadvantage. Four times a day, as a bonus action the size of the blade can be changed such that it can be wielded by a creature of any size other than medium. Only one bonus action is required to increase the blade to a certain size, however, for each size the blade is increased or reduced one use of its ability is consumed. For each size the blade is increased above medium, the number of damage dice rolled for the blade, its size, and the number of creatures that can be hit by a single strike is doubled. For the sake of determining how many creatures can be hit by a single attack of the blade, a creature is counted twice for each size above medium, to a minimum of one. Whenever a spell, ability, or feature causes the blade's wielder to grow or shrink, the blade will be enlarged or reduced accordingly, always matching its wielder's size. If the blade is of a size greater than its wielder's size, attacks made with it are made with disadvantage and without the attack roll modifier, unless this modifier is negative. The blade does not receive additional damage or a damage penalty due to spells such as enlarge or reduce.