Longspike (Very Rare)

The longspike grants its user the ability to strike from afar, without resorting to the use of unwieldy polearms. When grasped with force, the long, narrow blade extends, increasing the reach of its wielder's thrust, and can implant a rapidly-growing net of hyphal tethers that can bind and constrict a foe. You gain a +2 bonus to attack and damage rolls you make with this magic weapon. While attuned to this weapon it gains the Hyphal Parasite property.

Hyphal Stretch: On your turn, you can squeeze the longspike (no action required), causing it to lengthen and increasing the reach of melee attacks you make with it by 5 feet until the end of your turn.

Optional Attunement: You can choose to attune to this weapon, causing it to gain the Hyphal Grasp property while you remain attuned to it.

OA: Hyphal Grasp: As a bonus action while holding the rapier, you can speak its command word to cause writhing hyphal filaments to grow from it. The next time you hit a creature with a weapon attack using longspike within the next minute, the target must succeed on a DC 16 Strength saving throw or be restrained by the magical hyphae for 1 minute. An affected creature can use an action to repeat the saving throw, ending the effect on a success. After you activate this property, roll a d6. On a 1-2 you can't activate this property again until the following dawn.

OA: Hyphal Parasite: When you hit a creature with this weapon you can use a bonus action to cast the fungal infection spell on it (save DC 16, no concentration required). After you activate this property, roll a d6. On a 1-2 you can't activate this property again until the following dawn.

Finesse: When making an attack with a finesse weapon, you use your choice of your Strength or Dexterity modifier for the attack and damage rolls. You must use the same modifier for both rolls.

Proficiency: martial, rapier Source: Heliana's Guide to Monster Hunting - Part One p. 460, Player's Handbook (2014) p. 149