An Aethernaut specializes in navigating between the planes and rapid transit. Aethernauts exploit their knowledge of hidden paths and portals to freely move about the battlefield and to alter their attack's trajectory, magnifying its power.

Tools for Travel

3rd-level Aethernaut feature

You gain proficiency with Navigator's Tools. If you already have this proficiency, you gain proficiency with one other type of artisan’s tools of your choice.

Aethernaut Spells

3rd-level Aethernaut feature

You always have certain spells prepared after you reach particular levels in this class, as shown in the Aethernaut Spells table. These spells count as artificer spells for you, but they don’t count against the number of artificer spells you prepare.

Whenever you gain an artificer level, you can replace one spell you gained from this feature with another spell of the same level. The new spell must be a conjuration or transmutation spell from the sorcerer, warlock, or wizard spell list. Appropriate spells might include Thunder Step and Far Step from Xanathar's Guide to Everything.

Aethernaut Spells

Artificer Level	Spell
3rd	jump, protection from evil and good
5th	misty step, rope trick
9th	blink, sending
13th	banishment, dimension door
17th	planar binding, teleportation circle

Micro Gate Researcher

3rd-level Aethernaut feature

From your early studies into the planes, you learn the best path is seldom a straight line. As an action, you can temporarily create linked teleportation portals, called Micro Gates, a number of times a day equal to your Intelligence modifier (minimum 1), and regain all uses after a long rest. A small portal, just large enough in diameter to fit a weapon, arm, or tiny creature through, opens within 5 feet of you. The first Micro Gate is tethered to you and remains within 5 feet of you, even as you move. Additionally, a second Micro Gate emerges at a point that you can see within a maximum distance of you equal to 20 feet times your Proficiency Modifier (minimum 2). If the second portal would open in the space occupied by a creature, it instead opens within 5 feet of it. The Micro Gates remain for one minute, until you dismiss them as a bonus action, you manifest another pair of portals, or you’re incapacitated.

The portals are two-dimensional rings, hovering at a height of your choice from the ground and perpendicular to it at the points you choose. A portal ring is visible only from one side (your choice), which is the side that functions as a portal. Any creature or object entering the portal exits from the other portal as if the two were adjacent to each other; passing through a portal from the nonportal side has no effect.

You can manipulate your Micro Gates in the following ways:

• On your turn, you can move the second Micro Gate up to 30 feet in any direction (no action required). If a Portal is ever more than the maximum distance from you at the end of your turn, it closes.
• As a bonus action, you can rotate either portal ring so that the active side faces in a different direction.
• When you take the Attack action on your turn, any attack you make with that action can originate from your space or the second portal. You make this choice for each attack.
• When a creature that you can see within 5 feet of your second portal moves at least 5 feet away from it, the creature provokes an opportunity attack from you.

Astral Transfer

5th-level Aethernaut feature

You discover a breakthrough in the study of planar travel and learning to step beyond the material even before accomplished arcanists. As an action, you can conduct an Astral Transfer, casting the teleport spell with this feature, without expending a spell slot.

When cast this way, the destination must instead be on another plane of existence, and the total number of creatures you can transport equals 1 plus your Intelligence modifier (minimum 1). When the GM rolls the d100 to determine whether your arrive on target, you may add your Navigator Tools proficiency to the result, potentially saving you from straying far off course.

Once you use this feature, you can’t use it again until you finish a long rest.

Ethereal Leap

9th-level Aethernaut feature

You extrapolated information from your extensive planar travels to maximize shorter range teleportation magic. When you cast a spell or use a feature that allows you to teleport a number of feet, the range of the spell and the distance you travel increase by an amount equal to five times your Intelligence modifier. 

Your linked portals, if any are active, also move the same distance.

Telemetric Defense

15th-level Aethernaut Feature

Your ability to move between planes enables you to effortlessly slip through the planar boundaries to lessen the harm done to you during battle. When you take damage from an attack, you can use your reaction to give yourself resistance to all of that attack’s damage on this turn.