This weapon was made from a obsidian meteorite with unknown properties. Crafted without heat it its molten material shatters very easily. It is an ancient weapon that has several magic properties. Its first form was malleable but firm like some semi-solid solutions kids might play with. But while being crafted it was set in freezing temperatures to often making it freeze almost like that of the crystalline makings of ice. It cannot break as long as it is attuned to a user as its magic properties slowly attune to the user. An excess of heat like fire, magma or any other heat source can easily change it's form naturally but it hardens greatly at any sign of cooling. During various tempering and testings this weapon is able to be wielded in 1 magical form and 3 other alternate forms. All attacks from this weapon are counted with magic properties to bypass resistances and immunities. This weapon cannot be wielded by a non-magic user. 

Shattered:

Ranged Magic Attack: range: Each shard can reach 15ft further than the next furthest shard (practically infinite range) 2d10+10 Piercing Damage & 2d4 Cold Damage

Complete:

Melee Magic Weapon Attack: Range 30 Ft, 12d6 Slashing Damage

Molten:

Melee Magic Weapon Attack: Range 15ft, 12d4 Bludgeoning Damage & 3d4 Fire Damage

Churning:

Melee Magic Finesse Attack: Range 50ft, 4d6+6 Fire Damage & 4d6+12 Slashing Damage

If this weapon is held by a non-Elemental, Construct, demon or aberration then half the hit die and all fixed damage becomes 0. 

Proficiency with a Greatsword allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Weapon Property: Heavy, Must succeed 4 Dex and 1 Wisdom saving Throws during a full moon to use during battle, rolls can be done on separate days. , Heavy, Two-Handed, Graze