Is there an "anchor" or "weight" spell?

Question

My campaign calls for a spell that makes an object either immovable or immensely heavy. I haven't found one yet.

Is there a spell in the Core Rules or any of the Unearthed Arcana or other expansions that makes an object immoveable or otherwise drastically increases its weight?

If no such spell exists, but you can find an existing spell in Pathfinder or an older edition of D&D that accomplishes the same thing, please inform me of the previous edition so that i might use it as the basis for a homebrew spell.

Answer 1

Spells

There is now one spell from Explorer's Guide to Wildemount that will make an object immovable, and one that will increase its weight. Then one that increase the weight only of a creature. Here they are:

Immovable Object

The spell immovable object has a 1 hour duration and it reads:

You touch an object that weighs no more than 10 pounds and cause it to become magically fixed in place.

Enlarge

The spell enlarge/reduce multiplies the weight of the object it is cast on by eight.

Possibly Flesh to Stone

The spell flesh to stone can turn a creature completely into stone, applying the petrified condition. This condition multiplies the weight of the creature by ten.

Magic Item

I know you didn't ask for objects, but I think it might be a possible answer the the problem you are trying to solve without a spell. There is a magic item in the DMG called the Immovable Rod which has a button, that when pressed become fixed in space and can't be moved until the button is pressed again, or something like 20 tons of force is applied.

Answer 2

Immovable Object

Explorer's Guide to Wildemount, which came out in 2020 (years after you asked the question), contains the 2nd-level spell Immovable Object (p. 187). The spell does exactly what you are asking for: it makes an object immovable. The spell description states:

You touch an object that weighs no more than 10 pounds and cause it to become magically fixed in place. [...]

If the object is fixed in the air, it can hold up to 4,000 pounds of weight. More weight causes the object to fall. Otherwise, a creature can use an action to make a Strength check against your spell save DC. On a suc­cess, the creature can move the object up to 10 feet.

Casting it at higher levels increases the spell's DC, weight limit, and duration.

Answer 3

Phantasmal Force may be the closest thing to achieving your desired results, if you find that using Wish seems like a cop out.

First, the easy spell: Wish. Technically, you can make this spell do anything you want it to do subject to DM approval. It's the ultimate get out of jail free spell.

PHB pg. 288; Wish

For a more mechanical flavour geared towards what you're asking:

PHB pg. 264; Phantasmal Force (only the pertinent parts quoted below, emphasis mine):

The phantasm includes sound, temperature, and other stimuli, also evident only to the creature.

While a target is affected by the spell, the target treats the phantasm as if it were real.

Basically, this would allow you to make an object effectively immobile or unmovable to a single target, for up to 1 minute (pending the target fails the saving throws).

Alternately, you could also have something undergoing a persistent Phantasmal Force cast at a higher level that has a permanent effect if it's part of a magical item effect, or through the use of a Wish spell. However this would be something the DM would have to approve.

Answer 4

There is no such spell, but there are alternatives

I also haven't been able to find a spell that does exactly what you want.

However, the same effect could be accomplished with an immovable rod (DMG, p. 175) or sovereign glue (DMG, p. 200). You could integrate the immovable rod into the object, or rule that that object has the same enchantment as the rod. As for sovereign glue, you could use it to stick it to the ground (or whatever the object is resting on).

It is worth noting that D&D 5e gives DMs very large leeway for creating their own spells, so I don't really think you need an antecedent to make a spell. It depends on your players, I suppose, but whenever I need a magical effect, I just have it happen and say it's "magic".

Answer 5

Pathfinder: Lighten Object

You mention being open to a suggestion from Pathfinder, so you might be interested in the Lighten Object spell. It's a level 1 spell which halves the weight of an object (with some limitations).

If you are open to some marginal homebrewing, this gives you some basis for a "Weight Object" spell which doubles an objects weight. Just use the same parameters as Lighten Object.