I made a homebrew cantrip, detailed below. It is inspired by the "Geyser" option of the decanter of endless water.

I don't know if it’s super OP or on the weak side, so I want your opinion to make sure it’s balanced against other cantrips.

Water Beam

Conjuration cantrip

Casting Time: 1 action
Range: 30 feet
Components: V, S
Duration: Instantaneous

Spell Lists: Druid, Wizard, Sorcerer

You shoot a geyser of water in a line 30 feet long and 5 feet wide. Each creature in the line must make a DC 13 Strength saving throw. On a failure, the creature takes 1d4 force damage and is knocked prone; on a success, the creature takes the damage, but is not knocked prone.

  • \$\begingroup\$ Is it intentional that there's not any kind of roll needed to hit? You just pick a direction and anyone in the path gets hit for 1d4 damage? \$\endgroup\$ – Mark Wells May 20 at 22:33
  • \$\begingroup\$ Also, is the strength save supposed to be against the caster's spell save DC, or is it a fixed value of 13? \$\endgroup\$ – Mark Wells May 20 at 22:33
  • \$\begingroup\$ Here is a link to the revised version: (Revised) Is this Homebrew cantrip balanced? Water beam \$\endgroup\$ – Straight up oof May 20 at 23:03

Overpowered, underpowered and a bit odd

First of all, spells in DnD 5e don't usually have fixed DC spell saves. Rather, the save DC is the caster's spell save DC which is based on their spellcasting attribute.

Cantrips also usually scale with level. This one doesn't, which means that even if it was balanced initially, it would be weaker than other cantrips by level 5 which is when cantrips usually gain their first upgrades.

Compared to other cantrips for a level 1 caster, this is quite powerful for a variety of reasons. It deals guaranteed damage – even if little, it's a rarity for cantrips. It can damage multiple targets at the same time (also uncommon, but not unheard of, for cantrips), and potentially knock several of them prone which is a considerable bonus as it grants advantage on melee attacks against these targets while causing them to attack at a disadvantage.

For a somewhat similar cantrip, see Vicious Mockery, which deals 1d4 damage (at 1st level) on a failed save only, and imposes disadvantage for a single attack.

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  • \$\begingroup\$ I now realize issues with the spell and I am ready to revise it thank you \$\endgroup\$ – Straight up oof May 20 at 22:36
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    \$\begingroup\$ @Straightupoof If you want to do that, please read the guidelines here about the process for reviewing homebrew that's under development. A common mistake is to revise the version you've already put up for review--this makes the existing answers nonsensical and generally makes it hard to keep track of what's going on. \$\endgroup\$ – Mark Wells May 20 at 22:40
  • \$\begingroup\$ You say that cantrips having guaranteed damage is a rarity. Is there any cantrip that always deals damage? I think another good comparison would be to sapping sting which involves a saving throw to deal 1d4 damage to one target within 30 feet and knock them prone \$\endgroup\$ – Medix2 May 20 at 22:54
  • \$\begingroup\$ @Medix2 I was thinking the better comparison would be magic missile, since this both hits automatically and (because it's force damage) gets around damage type resistance. \$\endgroup\$ – Mark Wells May 20 at 23:16
  • \$\begingroup\$ @MarkWells Maybe even both, similarities all around \$\endgroup\$ – Medix2 May 20 at 23:17

Overpowered and unusual

This spell is pretty unique among cantrips, but that is likely a good thing as it makes it worth taking. However, the mechanics aren't quite right in this current version.

Fixed Spell Save DC

As a cantrip, this spell should use the caster's spell save DC rather than a fixed value. You don't need to specify the DC as part of the spell.

Automatic Damage

There are no official cantrips in the game that deal damage on a successful save. While spells typically have a successful save do half damage and negate side effects, successful saves against cantrips negate the effects entirely for that creature.

Area of Effect

Currently there are only a few cantrips with areas of effect: Sword Burst, Thunderclap, and Word of Radiance. Notably, all three share two features: a 5-foot radius centred on the caster, and 1d6 damage.

A 30-foot line is distinctly better than a 5-foot radius; it makes it a lot easier to line up multiple targets without putting yourself in danger or relying on them to be close to each other. This makes your cantrips stronger than any of the existing AoE cantrips.


Given the increased area of effect, I actually think 1d4 was a good choice here. It goes a long way toward making the spell more balance. One thing to remember, though, is that damage cantrips scale with level. Typically this would mean including a section like:

The spell's damage increases by 1d4 when you reach 5th level (2d4), 11th level (3d4), and 17th level (4d4).

Applying a Condition

Knocking a creature prone is a powerful benefit, particularly if you can do it right before your allied fighter's turn. There is currently only one cantrip that applies a conditions such as prone, though some others have additional one-time effects (such as Vicious Mockery, which imposes disadvantage on the target's next attack roll).

Sapping Sting, from the recently released Explorer's Guide to Wildemount, deals 1d4 necrotic damage and causes the target to fall prone on a failed Constitution saving throw. Importantly, it is a single-target effect, so yours is strictly better as it deals the same damage and effects but can target additional creatures.

I would suggest removing this effect entirely; it makes the spell much more in line with a leveled spell rather than a cantrip, and is therefore overpowered.


The current version of this spell is overpowered and has a few features that don't align with how cantrips usually work. When developing the next version, I suggest comparing your spell against other existing cantrips in the game.

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