King Crab Claymore (Patreon)

Weapon (greatsword), rare (requires attunement)

You have a +1 bonus to attack and damage rolls made with this magic weapon. While you're attuned to the weapon, crabs and giant crabs are indifferent toward you and will not attack you unless you threaten or harm them. In addition, crabs and giant crabs understand the meaning of your words, though you have no special ability to understand them in return. You have advantage on ability checks you make to influence or interact with crabs.

The sword emits a brief, fiery glow when you roll initiative. Until the end of your first turn of combat, attacks with the sword score a critical hit on a roll of 18, 19, or 20. When you score a critical hit with the sword for the first time on a turn, the target of the attack is also assaulted with crab-like claws made of fire. That target must make a DC 15 Dexterity saving throw, taking 2d6 fire damage on a failed save, or half as much damage on a successful one. On a failed saving throw, the target is magically grappled (escape DC 15) by the flaming pincers for 1 minute or until it successfully escapes using an action. Until the grapple ends, that target takes 1d6 fire damage at the end of each of its turns.

"Looks like it's time for a crab boil, fellas, and it's my favorite kind: the one where you get boiled by the crab."