Perhaps the most difficult group of spells to design, utility spells walk a fine line between being too weak or narrow (and never seeing play, like illusory script) or too powerful (a flying spell at 1st level is a poor choice). These spells can occasionally offer some unexpected combat utility, such as levitate (Player’s Handbook, or PHB) being able to target an enemy and lift them up into the air, where they cannot reach anyone with melee attacks. A lot of the time though, these spells are so non-combat-oriented that they feature the option to be cast as a ritual. The ability to breathe water or detect magic is handy, but in the middle of a fight it is unlikely to come up.
Utility spells solve problems and open new possibilities that did not exist before. There are a number of sub-categories utility spells could fall into, such as movement abilities like levitate, spider climb, fly, passwall, or teleport (PHB), divinations to spy from afar or ask yes/no questions such as augury, clairvoyance, scrying, arcane eye, or contact other plane (PHB), illusions to fool people such as minor illusion, silent image, major image, or hallucinatory terrain (PHB, also illusions can be battlefield control spells), and countless more.
The real crux of what makes a utility spell is that it provides some sort of new option or utility that did not exist before. They can be extremely narrow, such as feign death (PHB), or incredibly flexible, such as major image (PHB). If you want your players to use the spell, a versatile option is better than a narrow one. However, if you are designing a spell for an NPC villain, a narrow function is fine. If the players defeat them and learn the spell from their spellbook, and decide they want to use it, that’s great, but it might also collect dust after the villain is gone. In Spells from Elsewhere, I designed a noir detective spell called hematomancy (1st level), which lets you see a vision of how the blood was spilled. This would obviously be useful in crime scene investigation. To make the spell a little more broadly useful, it also has an augury/oracular function where you make a cryptic prediction about a creature you draw blood from using Intelligence (Arcana or Religion). It is a flavorful spell that would be great in an investigative game, but don’t expect any players to take it on a typical adventure. Instead, the best detective among the city watch might be a spellcaster who learns about crime scenes this way in your setting.
Rituals are hard to design, because it is difficult to come up with cases when you would spend a spell slot on the ritual, and I think it’s a nice tension to build into the spell. There are ways to change the functionality when cast normally or cast as a ritual, I played around in this space a lot with Ritual Magic. For example, a ritual spell is normally a bit weak when prepared as a normal spell and cast at its normal 1 action casting time… but what if the spell was a bonus action? Or a reaction? You might need to add some text to the reaction spell, letting people know that the trigger is no longer necessary when cast as a ritual. The spell is still normally weak, but it might have occasions where the player would genuinely be tempted to use a spell slot on it.
Rituals generally don’t affect game statistics or combat, but there’s some wiggle room if you look for it. The 3rd level antler rite from my book Ritual Magic is a bonus action to cast, and turns you into a deer. A deer is a far cry from what a druid’s wild shape is capable of, it is fast at 50 ft. movement speed but it cannot climb, swim, or fly, and it is not small enough to slip through holes or under doors (it could jump over a 10 ft. wall or onto a rooftop, if your Storyteller rules in favor of how deer jump in the real world). It technically gives you 4 additional hit points, 12 passive Perception, and a bite attack, but it’s almost more of a liability as a combat form at AC 13. As a ritual, it lets you scout an area in a relatively innocuous animal form, but there is a chance you would use it in combat to gain the 50 ft. movement speed to move and Dash action away. The change to a bonus action made a big difference.
Every class features some amount of utility, but this is an area where wizards truly outshine most other classes. Bards, druids, and sorcerers also have an amazing array of utility, though bards and sorcerers are tightly limited on spell choices. Artificers and clerics offer a fair share of utility, and warlocks can as well, especially warlocks that take the Tome of Shadows for rituals. Rangers can choose some utility options, and paladins are probably the worst at this category – don’t mistake their support spells as being utility spells.
LET’S MAKE A UTILITY SPELL
Speaking of paladins, let’s say you have a player whose paladin is having trouble deciding between different types of armor. As soon as two sets of magical armor with different properties become available, it becomes a choice of what to wear during any short or long rest. If they have a Dexterity modifier of +1 or +2, there might be times when they would prefer medium armor over heavy armor, and the ability to make a Stealth check without disadvantage. There could even be utility in rapidly doffing armor targeted by heat metal. Whatever the reason is, the player has asked you about developing a spell to quickly change or remove armor. You never expected spell research from the paladin, but now there’s a problem to be solved.
First, there is no reason to make this spell a ritual, because armor can already be changed within a 10-minute timeframe. Also, bear in mind that rangers, paladins, sorcerers, and warlocks do not innately have ritual casting (warlocks can gain it through their Pact of the Tome feature). You decide on the school of conjuration, because the armor is being teleported on and/or off of the target.
Second, this spell has very narrow application. The effect seems completely fair as a 1st level spell. It is fine to let it use a bonus action rather than an action, letting the character attack normally. Using just a verbal component is fine, we want combatants to be able to cast this spell with their hands full of weapons and shields. You don’t want the spellcaster to be able to remove the armor of their enemies, but letting an ally rapidly change or doff armor seems fine. Willing creatures can be targeted at a range of touch; a bigger range would be fine, but paladins already have a touch-range theme built into their class with Lay on Hands and various clerical spells, so it feels right here.
As for the other classes, in this case armor-wearing spellcasters feel like the appropriate group. Artificers, bards, clerics, druids, rangers, and warlocks join the paladin for class availability. Let’s admire our finished spell.
CHANGE ARMOR
1st level conjuration
Casting Time: 1 bonus action
Range: Touch
Target: One creature
Components: V
Duration: Instantaneous
Classes: Artificer, Bard, Cleric, Druid, Paladin, Ranger, Warlock
You or a willing creature touched may instantly doff (remove) any armor worn and can choose to don (wear) a different suit of armor. The new suit of armor must either be in that creature’s possession, in your possession, or be an unattended object you can touch. Doffed armor is placed in the target’s backpack or otherwise strapped or hooked onto their back, or the target can choose for it to appear on the ground at their feet.
If the new armor requires attunement as a magic item, this spell does not provide attunement if the target was not already attuned.
I’m Lord Rumfish, veteran dungeon master of Dungeons & Dragons and published author on DMsGuild (see my publications here: https://www.dmsguild.com/browse.php?author=Mark%20Burton&affiliate_id=1059803 ).