If I attempt to use the Teleport spell to teleport into an area warded by the Forbiddance spell, is my spell slot expended?

Question

From the Forbiddance spell description:

For the duration, creatures can’t tele⁠port into the area

A character may not know the area is warded by Forbiddance, attempt to cast Teleport to enter it, and fail. If they do, does that cost a spell slot?

When a character casts a spell, he or she expends a slot of that spell's level or higher

So my question is: if creatures can't teleport into the area, can they even cast Teleport targeting the area?

As a DM, if a player says "I cast Teleport to enter the area", do I say "you can't cast Teleport to enter that area", or do I say "you cast Teleport, but nothing happens"?

Answer 1

The spell slot is used

There is no RAW statement about failure when casting spells except under spells that take a longer casting times:

Certain spells (including spells cast as rituals) require more time to cast: minutes or even hours. When you cast a spell with a casting time longer than a single action or reaction, you must spend your action each turn casting the spell, and you must maintain your concentration while you do so (see "Concentration" below). If your concentration is broken, the spell fails, but you don't expend a spell slot. If you want to try casting the spell again, you must start over.

However, teleport is an instantaneous spell and your concentration is not broken--you are casting the whole spell.

So we look at two other spells that can block magic/travel: Globe of Invulnerability and Antimagic Field.

Globe of Invulnerability states:

Any spell of 5th level or lower cast from outside the barrier can't affect creatures or objects within it, even if the spell is cast using a higher level spell slot. Such a spell can target creatures and objects within the barrier, but the spell has no effect on them.

So one spell is preventing the effects of another. It is implied that the spell is cast, and that the slot used, but it has no effect.

A closer spell is Antimagic Field where it calls out teleportation:

Spells and other magical effects, except those created by an artifact or a deity, are suppressed in the sphere and can't protrude into it. A slot expended to cast a suppressed spell is consumed. While an effect is suppressed, it doesn't function, but the time it spends suppressed counts against its duration.

Magical Travel. Teleportation and planar travel fail to work in the sphere, whether the sphere is the destination or the departure point for such magical travel.

Much closer to what is happening in the Forbidden spell. It suppresses teleportation magic in, but doesn't stop the caster from trying and expending a spell slot.

And as AndrewK mentions is his answer; this is only relevant if the teleport is "On Target". Per the Teleport spell, it's entirely possible that the casting doesn't even resolve within the area of the Forbiddance spell. So first the spell is cast using a spell slot, then it is determined if the caster ends up in the Forbidden Zone or somewhere else, and then finally the spell is rebuked with no effect.

Answer 2

In short, yes, the spell slot is consumed. They cannot teleport into the Forbidden area, but things can still happen.

What the rules say

From the SRD: "Preparing and Casting Spells ... To cast one of these spells, you must expend a slot of the spell's level or higher."

Casting the spell is one thing. The spell taking effect (or not) is a separate thing.

To give a point of reference: It's fundamentally the same as casting Charm Person on someone who is immune to the charmed condition, and little different from someone making their saving throw.

To get into the details more, the Teleport spell would be cast and would evaluate as normal up to a certain point. The spell slot is consumed, and the DM (or whoever) rolls the d100. The Teleport may go wibbly-wobbly all on its own. The Forbiddance is only relevant if "On Target" is rolled, in which case you decide what happens. Forbiddance does not say, so it's up to the DM to make a judgment.

How you make up for the rest

There are as many possibilities as there are DMs in the world, but here's how I'd run it:

Different spellcasters' spells work differently. Does the Forbiddance prevent teleports by making them "bounce," by absorbing/dismantling the magic, or by preventing the Teleport from the finding its target?

If it bounces Teleports away, I'd reroll the Teleport table, and On-Target lands near the Forbiddance boundary.

If it absorbs or dismantles the Teleport, the players would go nowhere, and the spellcaster using Forbiddance may even capture the Teleport's magic for some purpose! (Scrying, or a counter-Teleport, perhaps)

If it prevents the Teleport from finding targets within the area, the Teleport would resolve to the closest it can find, which depends on the description. If the player targeted the spell using geographic positions, "Off-Target." If the player targeted the spell using a description, "Similar Area."

Answer 3

The spell simply fails.

The spell description for Forbiddance directly states that creatures cannot go into the area (as quoted by yourself) by teleportation of any means, until it is dispelled, or it's duration maximum is reached. The character still expends the spell slot, as they have prepared to as well as already casted Teleport, even if the spell fails.

In the situation provided,

As a DM I would say "You cast teleport, but the spell fails- something is blocking your magic from moving your body to (insert location)." If the character casting Teleport does not know about the Forbiddance spell casted upon the location they wish to cast Teleport to get to.

Answer 4

The Spell Slot is used.

To my Knowledge the spellcaster is attempting to cast a spell therefore the spell slot is used up in the attempt. Though the attempt is nullified due to Forbiddance Which doesn't allow the spell to work.

Though this is ultimately up to the DM. If the DM wishes to be nice they can and say that the spell slot isn't used.