Glaive Dancer

You have mastered the art of fighting with a polearm. What others may see as an unwieldy and cumbersome weapon, you see as an elegant tool fit for nimble and fluid combat. You have dedicated yourself to the art of fighting with flowing, sweeping motions with your polearm, spinning and striking to confuse your enemies. This style had originated with the Drow, using the wicked magic of the Underdark to power their polearms with mysterious energy. However, some have shared this art with others, such as with the Kenku or with Humans that ventured into the Underdark. The source of this power no longer originates only from the Underdark, but as it is the place of the technique's birth, many still draw from its insidious elements.

A Glaive Dancer specializes in control over the battlefield, utilizing the size and power of their weapon to take the fight on their own terms. Through the power of the Underdark, you have access to a wide array of abilities that bolster your might whilst wielding a special polearm, your Shadow Glaive.

Shadow Glaive

When you choose this archetype at 3rd level, you gain the ability to channel shadowy energy through a polearm of your choice. You learn a ritual that creates a mystical bond between yourself and a glaive, halberd, pike, quarterstaff, or spear. You may perform this ritual over the course of 1 hour, which can be done on either a short or long rest. This weapon becomes your Shadow Glaive (it does not need to be a glaive), and you become proficient with it, but not other weapons of the same type. You can not affect an artifact or a sentient weapon in this way. When you attack with this weapon, you can use Dexterity instead of Strength for the attack and damage rolls. You can also use your Shadow Glaive to make a Sneak Attack in place of a weapon with finesse.

Once you have bonded your Shadow Glaive to yourself, you cannot be disarmed of it unless you are incapacitated. You may also shunt your Shadow Glaive into a small pocket dimension, concealing it from others without the use of an action. You may pull your Shadow Glaive out of this pocket dimension as a bonus action. 

You can have only one Shadow Glaive at a time. The weapon ceases to be your Shadow Glaive if you die, if you perform your Shadow Glaive ritual on a different polearm, or if you complete a 1-hour ritual to end your bond with your current Shadow Glaive. The polearm appears at your feet if it is in the extradimensional space when the bond breaks.

You also gain proficiency in the Performance skill if you don’t already have it.

Vicious Sentinel

Also at 3rd level, you gain the ability to trip an opponent attempting to leave your attack range. When you hit a creature that is no more than one size larger than you with an opportunity attack whilst wielding a glaive, halberd, pike, quarterstaff, or spear, you can make a Dexterity (Sleight of Hand) check contested by the target's Strength (Athletics) or Dexterity (Acrobatics) check (the target chooses the ability to use). If successful, the creature is knocked prone. 

Glaive Dance

Starting at 9th level, the magic powering your movement is elevated. You gain the following dance maneuvers to use while you wield your Shadow Glaive:

Deflecting Spin. By twirling your Shadow Glaive, you can create a ghostly shield to protect yourself from ranged attacks. You can use your reaction to block or deflect a ranged weapon attack. When you do so, the damage is reduced by 1d10 + your Dexterity modifier + your Constitution modifier. If you reduce the damage to 0, you can deflect the projectile at a creature within range. Make a ranged attack with a range of 20/60 using the weapon or piece of ammunition you just deflected as part of the same reaction. You make this attack with proficiency, regardless of your weapon proficiencies.

Graceful Retreat. You have mastered the use of the pocket dimension you use to conceal your Shadow Glaive. As a bonus action on your turn, you may jump into this pocket dimension with your Shadow Glaive, appearing in an unoccupied space within 30 ft of where you disappeared that you can see. Each creature of your choice within 5 ft of where you reappear takes 1d6 necrotic damage. This ability’s damage increases by 1d6 when you reach 13th level (2d6) and 17th level (3d6). 

Shadow Strike. Using the abundance of energy from your Shadow Glaive, you can create an afterimage of a strike that you had just made. When you take the Attack action with your Shadow Glaive, you can use a bonus action to make a melee attack with the afterimage of your first attack. This attack uses the same ability modifier as the primary attack, and uses 1d8 as its damage die, dealing necrotic damage. If you have the Polearm Master feat, you may make the additional attack from the feat in addition to this afterimage attack, using the same bonus action to do so. 

Sweeping Break. The wide reach of your weapon allows you the ability to strike multiple targets at once. If two or more creatures are within your attack range, you may take an attack on each of these creatures using a single action, however, each attack will have a -5 penalty to the attack roll. If every attack from this ability is successful, you deal an additional 1d4 necrotic damage to each target that was hit. 

You may only use one dance maneuver per turn, and you can use dance maneuvers a number of times equal to your proficiency bonus. You regain all uses of this ability at the end of a short or long rest.

Dancer's Movement

At 13th level, the dark magic that fuels your Shadow Glaive quickens your movement. You gain advantage on initiative rolls. 

Furthermore, your training with your Shadow Glaive has given you unnaturally quick reactions. You gain an additional reaction, allowing you to make two reactions per round of combat. You can not use both reactions within the same turn of each other.

Once you use this feature, you can not do so again until you finish a long rest, unless you expend a use of your dance maneuvers to use this feature again.

Reach of Shadows

Starting at 17th level, you have become adept with the darkness that fuels your attacks. Your Shadow Glaive pulls you toward an opponent's soul, increasing your reach and allowing you to strike at a creature's inner being. Add 5 ft to your reach when determining your reach for attacks, but not for opportunity attacks. 

Also, when you use your Shadow Glaive to deal Sneak Attack damage to a creature, you can have the creature make a Constitution saving throw (DC equal to 8 + your Dexterity modifier + your Constitution modifier). The creature takes 4d10 necrotic damage on a failed save, or half as much on a successful one. 

Once you use this feature, you can't do so again until you finish a long rest, unless you expend 3 uses of your dance maneuvers to use it again.