Balduran's Giantslayer

Balduran's Giantslayer is a legendary greatsword that receives doubled damage bonus from Strength, grants its wielder the Giant Form class action and the Topple the Big Folk weapon action, as well as Advantage on attack rolls against Large, Huge, and Gargantuan creatures.

Wielded by Balduran, the founder of Baldur's Gate and friend to his guardian dragon, a great glittering wyrm called Ansur. Fellowship can be undone, though, as easily as you or I might unlace the strings of our shoes, and it was in a time of skullduggery and hardship that Balduran killed Ansur, carrying out the deed with this sword.

Properties

Damage: 2d6 + 3 (5~15) + Strength modifier Slashing damage
Details: Greatswords; Rarity: Legendary; Enchantment: + 3; Two-Handed; Dippable; Melee: 1.5 m / 5  ft; Weight: 2.7 kg / 5.4 lb; Price: 1300 gp; UID
MAG_Giantslayer_Greatsword

UUID
7219fca3-5f41-43a0-8253-f4c09d8b6308

Special

The holder of this item gains:

Giantslayer: On a hit, double the damage from your Strength modifier. This weapon grants you Advantage on Attack rolls against Large, Huge or Gargantuan creatures.

Giant Form (): Grow to a fearsome size. Your weapons deal an additional 1d6 damage and you gain 27 temporary hit points and Advantage on Strength Checks and Saving throws. ( Recharge: Short rest).

Weapon actions

If you have proficiency, equip in main hand to gain:

Pommel Strike (): Make a non-lethal attack against an enemy and possibly Daze them.,
Lacerate (): Slash at your target's vital points to make it Bleed., and
Cleave (): Swing your weapon in a large arc to attack up to 3 enemies at once. They each take half the damage your weapon usually deals.

Special weapon actions

This weapon also grants the following:

Topple the Big Folk (): Deal additional damage equal to your proficiency bonus. On a hit, Large, Huge, or Gargantuan creatures take an additional 2d6SlashingDRS damage and must succeed a Strength saving throw or fall Prone.

Looted from Ansur in The Dragon's Sanctum, Wyrmway.

It is possible to grow two size categories larger than normal by combining this weapon's Giant Form with the Elixir of the Colossus.
Giant Form does not stack with the spell Enlarge.