Is this homebrew exfiltration spell balanced?

Question

Dimensional Anchor

3rd Level Conjuration
Casting Time: 1 action
Range: self
Components: V, S, M (a small, leaden nail worth 5gp)
Duration: 1 minute

You pound a nail into a point on a stationary surface, anchoring your being to the nail's location. During the spell's duration, you can utter a command phrase as a bonus action and magically teleport to the nail's location and the spell ends.

You can bring along objects as long as their weight doesn’t exceed what you can carry. You can teleport to the nail regardless of physical distance, planar distance, or obstacles (magical or otherwise, including barriers of magical force) between you and the nail. The effect occurs only if the command phrase is audible.

The nail can be moved by any creature, however you can only teleport to the nail if it is embedded in a stationary surface.

At higher levels. When you cast this spell using a spell slot of 5th level or higher, the duration of this spell increases to 1 hour.

The intended purpose of this spell is as an exfiltration tool that must be prepared before usage, with clear differences between Misty Step and Teleportation Circle. I've deliberately made its teleportation and escape potential much stronger than the others to offset the setup added cost of this spell, and as a way to reward creative thinking and good planning.

Is this spell balanced?

I've prepared a list of balance consideration to help guide analysis.

Balance Considerations

• I haven't determined which classes will be able to use it, so for the purposes of analysis, you may assume that any spellcasting class can use it.
• Comparison with Misty Step:
  • This spell is likely to be used in a similar manner as Misty Step--primarily a means of escaping a sticky situation. The escape potential for this spell is much greater, as it can be used to escape almost any bond or prison.
  • Misty Step can be cast reactively and requires a bonus action, whereas this spell requires a full action and bonus action. Action economy favors Misty Step in almost any scenario , unless the user has specifically approached a situation with a plan in mind.
  • This spell requires a spell slot of 3rd level or higher, while Misty Step requires only a 2nd level spell slot.
• Comparison with Teleportation Circle:
  • This spell is mainly intended as a short-term, higher flexibility counterpart to Teleportation Circle .
  • Teleportation Circle can be used to access any existing Circle, whereas Dimensional Anchor can only be used to return to a recent location. As such, Teleportation Circle has much higher travel utility.
  • Due to its lower casting time, Dimensional Anchor can be used mid-combat.
• Comparison with Word of Recall
  • This spell only works for a single creature (the caster) and has a finite duration.
  • This spell is significantly lower in level, meaning that it can be used more often at lower levels to avoid physical obstacles that wouldn't otherwise deter a high-level player.
  • The return location for this spell does not require special or cleric-related significance. This greatly increases its real-time flexibility.
• Silence prevents the user from teleporting via this spell.
• The nail can be moved by any creature--hostile or otherwise.
• (I'd edit the text but at this point there are answers so I'm leaving it as is) "obstacles" mean obstacles in the literal sense. An Antimagic Field is a only an obstacle in the figurative sense, so it would successfully block the teleportation effect.

Answer 1

The best comparison is dimension door

We can balance this spell by comparison to dimension door. That spell lets you teleport anywhere within 500 feet of you, with one willing ally; this spell lets you teleport somewhere that you were standing a minute ago (probably within 500 feet unless you're doing something very strange) and bring zero allies.

The decrease in flexibility from only being able to teleport to the place you put the nail (and only if you actually did the preparation) is worth a decrease of a spell level, so overall I think this spell is not overpowered. It might actually be underpowered since a one-minute teleport window is very narrow -- there's not much you can do in a single minute before your prepared teleport expires. Maybe change it to ten minutes?

There's one exception: you've told us that this lets you teleport "regardless of planar distance", and planar travel is too much for a third-level spell. Getting in trouble on an alternate plane normally requires plane shift (a seventh-level spell!) to get out of. This spell shouldn't be able to produce an effect of that magnitude.

This spell does offer a cheap return trip for a teleport spell. We can imagine that an NPC caster might use their seventh-level spell slot to teleport an adventuring party into a dangerous location, and then use dimensional anchor to return home.

But it's not clear who would use this

For a wizard who's part of an adventuring party, this seems like a bad spell. Pay a third-level spell slot up front, and then if something bad happens in the next minute, you can teleport away and leave the rest of the group to die?

A wizard who's about to perform some sort of solo adventure would find the spell very useful. But why is the DM running a D&D adventure about a wizard going on a solo adventure? The DM should make sure the whole group is involved in the game.

(Another way to put that: single-person teleport spells usually lead to splitting the party, and splitting the party is usually no fun.)

If someone told me they wanted to learn this spell, I'd probably remind them that my D&D game isn't supposed to be about them going on a solo adventure, and I'd ask them to think about spells they could get that would let them do things the whole group could be part of.

Answer 2

I've rewritten my answer now that more questions have been addressed.

Still more questions, but I am sure it is overpowered:

Define "embedded"

What is "embedded"? What is the requirements to do it? Can it be embedded in a block of wood and then moved at will? Embedded in a jar of sand so it's always ready?

It needs to be a concentration spell

This spell is fundamentally a blend of Expeditious Retreat and Misty Step. Misty Step does not require Concentration as it Instantaneous. But you're talking about something that can last between a minute and an hour. Without such a limitation, a caster could set up multiple way points. This would lead to a couple of loopholes:

• A caster can place a number of nails within a room in preparation. Then during combat they run up to the enemy, cast a powerful touch spell, then as a bonus action teleport back to any of the nails without risk of Opportunity Attack.
• A caster can place one nail outside a castle embedded in the ground, then embed a second nail into a piece of wood. As a guard walks in, put the wood in their knapsack. Wait some amount of time and then teleport into the castle and do whatever needs to be done. Then at the 59th minute, or right before discovery, zoom back outside. This works even if the caster is in an anti-magic cage, or imprisoned on a different plane.

There needs to be more limitations

The spell can work across any physical distance and across planes of existence. Given an hour of time this can be as powerful as a teleportation circle, dimension door, and/or plane shift. This gap can be widened both by movement of the caster and movement of the nail. This does not require line of sight, foreknowledge, or even a basic description.

• The spell can be cast and the nail handed to a familiar. The familiar can now place the nail anywhere the familiar can reach within time for a simple teleportation spell.
• The spell can be cast on two nails and one thrown into a deep crevasse. The caster can then teleport to the bottom without having to navigate down and then navigate back to the top where the second nail is waiting.
• Similarly, one nail can be thrown into a large body of water. With instance teleportation, there is no need to cast water breathing as the caster can just hold their breath. This may run into the issue of the the return word being "audible". You can still make sounds underwater, but they may not be intelligible.
• Nail it into an Earth Elemental, banish them with the nail, and then get "recalled" to the Elemental Plane of Earth.

How do you handle creatures?

Since a number of casters, there should be information or details on familiars, pets, and animal companions. This would be similar to Thunder Step.

"You can also teleport one willing creature of your size or smaller who is carrying gear up to its carrying capacity."

There is no limitation to the objects carried other than weight

This doesn't include the normal "if it isn't being worn or carried" clause, so could the caster touch something being carried and have it teleported away? Effectively disarming a person, or stealing a magic amulet.

• This would lead to the scenario of running up to an enemy, grab something, then teleport away with the object. This could be a weapon, a magic item, an arcane focus, or anything else disabling or greatly hindering one or more creatures. And as before, since this is teleport, there is no Opportunity Attack.

The can penetrate even magical barriers

You mention in the comments that specific beats general, but I think you're looking at it backwards. The general is that other spells/situations prevents teleportation, but this specifically says it care about magical barriers.

All these things mean the spell needs a lot of fleshing out

Answer 3

Bypassing Magical Obstacles is a problem

This is a third level spell. It's weird to let it negate Anti-Magic Field and other magical methods of preventing access. Methods like Anti-Magic Field which also prevent spellcasting are particularly weird since you can teleport in since the spell specifically bypasses obstacles like that, but you then can't cast the spell to get out because the spell's cheat-y bypass effect doesn't kick in until it's cast. You might not even be able to use the bonus action for other nails you have active, since such a field suppresses magic while you are there, further highlighting the spell's offensive bias as opposed to your stated defensive intent.

No range limitation is a problem

Since the range, like for sending et. al., is self, and the only limitation on where the nail goes is 'a stationary surface', this seems to let you effectively cast a super-extra-good transportation version of Plane Shift as a 3rd level spell. For example, you could cast the spell while on the material plane to put the nail in your heavily fortified citadel on the Astral, then again to put one in the floorboards of Mordenkainen's extradimensional mansion, then warp to the mansion, steal something, and warp to your citadel, all without traveling to either location at any point prior to the spell.

This also bypasses the main limitation you seem to think exists contra misty step-- namely that this spell requires set-up time. It doesn't; you can merely reduce the action cost from one action + one bonus action to one bonus action if you take set-up time. Even without set-up time, this spell can still teleport you to safety without any chance of failure within a single turn.

If you want the spell to be more reasonable and only let you hammer a nail in to a surface you are at, you need to say that. For example, limit the spell to nailing "a solid surface within 5' you can see", or change the spell's range to 5' and have it target the surface, which will also make you able to teleport out of but not into anti-teleportation zones, instead of the reverse.

This spell is so good, I would expect every Eldritch Knight and Arcane Trickster, at the very least, to always take it as their first 3rd level spell without fail. On that basis I think it is overpowered.

Comparisons:

Comparison with Misty Step:

This spell can be used in a similar manner as Misty Step--as a means of escaping a sticky situation, though it is primarily useful for getting into places. The escape potential for this spell is much greater, as it can only be blocked by preventing the caster from uttering the command word, whereas Misty Step can only teleport a character to a location the caster can see with an at-most-1-mile (via the Lore Wizard specialization) range.

Misty Step can be cast reactively and requires a bonus action, whereas this spell requires an action and bonus action except when time was taken to prepare within a minute of the combat (or an hour for the 5th level version). Since we are looking at escaping a combat, this is functionally the same action cost-- neither spell takes longer than the user's turn to escape, although Misty Step has a very slight advantage in the caster being able to take an action, rather than merely a free object interaction, to prepare before the teleportation.

This spell requires a spell slot of 3rd level or higher, while Misty Step requires only a 2nd level spell slot, which is a significant balancing factor, but this spell is nearly always better than Misty Step in every situation, even those Misty Step is most specialized at, despite having a completely different niche of its own as well. It beats out Misty Step-- one of the best second-level spells in the game-- almost as an afterthought to its main function, and that is reason to worry.

Comparison with Teleportation Circle:

Teleportation Circle can be used to access any existing Circle, whereas Dimensional Anchor can be used to access literally any solid surface anywhere the user wishes with no prior notice and nothing those at the destination can do to prevent entry. As such, Teleportation Circle has much, much lower travel utility-- the only benefits to that spell are that you can bring along schmucks who didn't take this one, and that if you take an entire year of set-up time, you can get a permanent effect that doesn't cost a spell-slot.

Dimensional Anchor doesn't beat out the (2 spell levels higher) Teleportation Circle spell in its niche-- i.e. transporting the party's non-spellcasters to new adventure locations and setting up interplanetary trade-- but it beats it out for every usage outside of that area.

Comparison with Word of Recall:

This spell only works for a single creature (the caster) and has a finite duration, and doesn't require you to have ever been at the location you want to teleport to, or even know very much about it. The only thing Word of Recall has going for it, like Teleportation Circle, is the mass-transportation usage.