Circle of the Mecha-Beasts

Druids of the Mecha-beasts circle have the same passion for nature and beasts as any druid, but are much more open-minded about technology. They combine their knowledge of mechanics and circuitry with the inspiration from natural creatures to become automatons of their own imagining. This circle lifts the class restrictions on metal armor and shields.

Mechanical Forms

At 2nd level, your circle grants you the ability to transform into a mechanical version of a beast. Whenever you use Wild Shape, you still choose a beast, but are considered the Construct type. This form has resistance to nonmagical bludgeoning, piercing, and slashing damage, and you gain a bonus to your AC equal to your Intelligence modifier. Additionally, you are immune to poison damage, and the exhaustion and poisoned conditions. 

Starting at 12th level, you can transform into a beast with a challenge rating as high as 2.

Overdrive

You gain the ability to use Wild Shape on your turn as a bonus action, rather than as an action.

Additionally, while you are in your mechanical form, you can use a bonus action to Dash, Disengage, or make a single attack. When you hit a creature with your mechanical form, you can expend one spell slot to deal additional lightning damage equal to 1d8 per level of the slot expended.

Weapon Installation

 Starting at 6th level, your attacks in mechanical form count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.

While transformed, you can also cast the spell Scorching Ray, without verbal or somatic components. You always have this spell prepared, and it doesn't count against the number of spells you can prepare each day. It counts as a druid spell for you and uses a spell slot as normal.

Arcane Machinization

When you reach 10th level, certain spells adopt more artificial characteristics.

• Entangle conjures a mass of wires and circuitry instead of plants. A creature restrained by this spell takes 3d6 lightning damage at the start of each of its turns.
• Barkskin gives the target a rigid, metallic appearance. The target's AC can't be less than 20.
• Conjure animals summons mechanical beasts. The fey spirits are considered constructs rather than beasts, they have resistance to nonmagical bludgeoning, piercing, and slashing damage, and they are immune to poison damage, and the exhaustion and poisoned conditions.
• Watery sphere conjures a sphere of highly flammable oil rather than water. If the sphere comes in contact with fire, any creature that is in the sphere's space takes 5d8 fire damage, and the spell ends (When the spell ends, the oil immediately evaporates).
• Insect plague conjures robotic locusts that are programmed to ignore certain targets. When you cast the spell, you can designate any number of creatures you can see. Those creatures do not take damage from the spell, although the light obscurement and difficult terrain may still affect them.

Adaptive Mobility

At 14th level, while in your mechanical form, moving through nonmagical difficult terrain costs you no extra movement, and each time you expend a use of your mechanical form, you can choose an extra form of movement: climbing, swimming, or flying, to gain while in the form. The extra movement is equal to your base walking speed.