This rare type of weapon is said to have originated in distant lands, where the raw chaotic nature of magic has been gathered in its purest form, and expertly weaved into the metal to produce this wonder of crafting ingenuity.

In its dormant state it present itself as a normal version of the base weapon, albeit beautifully crafted and engraved.
Upon attunement, the engravings start to shine shiftingly, passing through most colors of the spectrum and will gain the following abilities:

• During a short rest, the attuned user can choose a type of damage between Acid, Cold, Fire, Force, Lightning, Poison, or Thunder
• Until the next short rest the weapon will deal +2d6 damage of the chosen type on a hit
• If Acid is active as the designed additional damage type, the weapon will also corrode any non-magical material with max 10 HP and maximum thickness of 5 inches
• If Cold is active as the designed additional damage type, the weapon will also create a cold mist in a 10-foot radius around the user, snuffing any non-magical sources of flames up to maximum diameter of a regular torch and causing flame-based creatures within the radius to make a WIS saving throw (DC 12) or suffer disadvantage on attack rolls against the user until the end of their next turn
• If Fire is active as the designed additional damage type, the weapon will also shine bright light in a 40-foot radius and dim light for an additional 40 feet, set ablaze any non-magical flammable material it comes in contact with, and force any ice-based creature within 10 feet of the wielder to make a WIS saving throw (DC 12) or suffer disadvantage to attack rolls against the wielder
• If Force is active as the designed additional damage type, a hit will also cause the target to make a STR saving throw (DC 12) or be moved 5 feet in a chosen direction
• If Lightning is active as the designed additional damage type, the weapon will also shine bright light in a 10-foot radius and dim light for an additional 10 feet, and any successfully hit target wearing or being made mostly of non-magical metal will suffer an additional 1d4 Lightning damage
• If Poison is active as the designed additional damage type, a hit would also cause the target to make a CON saving throw (DC 12) or be Poisoned until the end of their next turn
• If Thunder is active as the designed additional damage type, the weapon will also create a loud boom on impact, alerting any creature in a 60 foot radius of the presence of the wielder and causing the target to make a WIS saving throw (DC 12) or be Deafened until the end of their next turn

Should a chaotic aligned creature try to attune to the weapon, at completion he would suffer 1d8 Force damage.
After that the weapon will behave differently, as follows:

• The weapon will require only an action in order to change from one damage type to another, instead of a short rest;
• The weapon will still deal +2d6 damage of the chosen type on a hit, but the user will suffer 1d6 damage of the same type

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

Notes: preferably non-chaotic creature, Damage, Combat, Versatile, Sap