The whirling dervish is a master of the steel dance, surrounded in an array of weapons that travel far and cut down their foes in acts that seem almost magical.
When you choose this archetype at 3rd level, you gain proficiency in one of the following skills of your choice: Acrobatics, Sleight of Hand, or Performance.
Also at 3rd level, you learn how to properly utilize the implement of your skill for combat. Over the course of a short or long rest, you can create and attach tensile rope to weapons with the thrown property. You can select up to a number of weapons equal to your proficiency bonus. You can wield two weapons with tensile rope attached in a single hand. At the end of your turn, any thrown weapons with tensile rope attached return to your hands with a flick of your wrist (no action required by you).
Additionally, you can use your dexterity modifier for any ranged attack made with a thrown weapon.
Starting at 7th level, you gain expertise in one of the following skills of your choice with which you have proficiency: Acrobatics, Sleight of Hand, or Performance.
As an action, you can begin the Steel Dance, which lasts for one minute while you have at least one weapon with tensile rope equipped or until you lose concentration (as if you were concentrating on a spell). Immediately, and at the beginning of every subsequent turn while the Steel Dance is active, any number of creatures of your choice within a 20-foot radius centered around you must make a Wisdom saving throw contested against a DC of 8 + your proficiency bonus + your Dexterity modifier. On a failed save, a creature has a movement speed of 0, suffers disadvantage on Perception and Dexterity checks and saves, and has their Passive Perception lowered by 5. The creature can choose to repeat this save at the end of each of its turns. On a successful save, the effect ends and the creature is immune to Steel Dance for 24 hours.
As part of the action taken to begin the Steel Dance and while Steel Dance is active, you can take the Attack action. You can only use subsequent turns to take the Attack action while Steel Dance is active. Immediately after being hit by you, a creature can reattempt its saving throw against Steel Dance. You can end the Steel Dance early (no action required by you), and the effects of the Steel Dance end on any creatures affected by it.
You can use this feature a number of times equal to your proficiency bonus, and you regain all expended uses of it when you finish a long rest.
Starting at the 10th level, the area of your Steel Dance becomes difficult terrain for hostile creatures, where 1 foot of movement costs 3 feet. Additionally, you have advantage on all Concentration checks to end Steel Dance.
At the 15th level, the area of your Steel Dance expands to 30 feet. Additionally, you regain all expended uses of Steel Dance when you finish a short or long rest.
Starting at 18th level, your Steel Dance becomes a whirlwind of death. All attacks made during Steel Dance have the size of their die increase by one, and you can no longer lose concentration on Steel Dance.