The Tempest is a whirlwind of steel. By using two weapons, the Tempest launches a series of devastating blows against their opponents. They become a dervish of whirling steel, launching themselves in the middle of combat to strike at nearby enemies, often sacrificing their own defenses and safety to do so. 

Steelwind Strike

At 3rd level, you learn to launch yourself into battle and unleash a multitude of attacks. 

When using a melee weapon in each hand, you may use a Bonus Action to activate this ability. While Steelwind Strike is active, whenever you make an Attack action with a melee weapon attack, you may make an additional attack against each enemy within range of melee weapon attack as part of that action. This attack may be done with either weapon. In addition, whenever you make an Attack action under this effect, you may move up to half your movement speed. Opportunity attacks against you during this effect movement have disadvantage.  This effect lasts until the start of your next turn. 

You may use this ability a number of times equal to your proficiency modifier per short or long rest.

Tempest Training

Starting at 3rd level, you become proficient in both the Acrobatics and Athletics skills. In addition, you gain Expertise in one of those two skills. Expertise doubles your proficiency bonus when using that skill.

Expertise in Acrobatics

You have expertise in the Acrobatics skill. Expertise doubles your proficiency bonus when using that skill.

Expertise in Athletics

You have expertise in the Athletics skill. Expertise doubles your proficiency bonus when using that skill.

Quick and Efficient

Beginning when you choose this archetype at 3rd level, when using a melee weapon in each hand, your weapon attacks score a critical hit on a roll of 19 or 20.

In addition, you gain proficiency in Dexterity saving throws. 

Leaping Vortex

At 10th level, your Steelwind Strike empowers you to launch yourself into battle. 

Whenever you use Steelwind Strike, your movement speed doubles while the effect is active. In addition, you now ignore opportunity attacks while under this effect. You may also take a long Jump after just five feet of of movement and your jumping distance increases by an amount equal to double your Dexterity score or Strength score (your choice). 

In addition, when you roll Initiative and have no uses of Steelwind Strike left, you regain one use. 

Frenzy of Steel

You launch yourself into a frenzy of action, becoming a blur of attacks. While your defenses are lowered, you strike at the enemy even more. 

Starting at 10th level, whenever you use your Steelwind Strike feature, you may choose to suffer a negative 5 penalty to your AC. If you do so, you may gain yet another attack against every enemy within reach of your melee weapon attack as part of the Attack action while under this effect. This attack can be used with either weapon. 

Overwhelming Winds

Starting at 18th level, you have become an unstoppable whirlwind.

When wielding a melee weapon in each hand,  your weapon attacks score a critical hit on 18-20. In addition, when using Steelwind Strike, if you roll a 18-20 on your attack roll and critically hit, you may make yet another attack as part of that action.