Low Magic System (5e Variant Rule)
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Low magic system
In D&D 5e most PHB's classes are spell caster. Half of the classes are full spell casters and 2 classes are half spell caster. This is a problem in low magic world. In a world where spell casting is rare, most of the classes would not fit.
The goal is to keep spell caster classes without nerfing them. It is equivalent trade. For a weaker spell casting ability, they gain more ability. In the ideal world, martial (non spell casters) and spell casters should be equally strong. We aim to create a D&D world where most of the 12 classes exist. They have weaker spell casting but not weaker class.
This guide will give tips and tricks on reducing magic aspect of D&D 5e. As a GM, you can pick and choose which one will work best in your world. There is no need to take all of them. They are here to inspire ideas and rules for a low magic world.
Spell casters in the world
The most simplest and easiest way to reduce the number of spell casters is that they have a bad reputation. People are shunned from learning spells. Most spell casters are not well liked. Make spell casters closer to sewer cleaners, no one wants to be a spell caster. They will have a hard time to make friends and many would not be friendly (but not unfriendly) when they first see them.
Do NOT have "witch" hunts to kill spell casters. It should not prevent them from buying items or staying at an inn. It should not make the guards want to arrest them for the very little things. At worst, spell casters can be consider as a low class citizen. They have rights and protected by the law.
To make this work, make sure that the players know that spell casters and magic is not liked by majority of the population. This is the most important step to discourage spell casters.
Some feats grant magic ability. Any feats that gives cantrip, new spells, or once per day spells are removed. Metamagic feat is removed. Feats that improve spell casting like war caster is allowed.
Some races have magical abilities. Replace radial's cantrip with skill proficiency. All mention of spell casting is replace with 1 ability score increment or 1 feat depending how important is spell casting is to that race. Balance the new race against variant human.
Secret high level spells
The maximum spell level that class could learn, it cannot be learn normally. The player must find a teacher or a scroll containing a that spell to learn it. This gives higher level spell more meaning and GM con control what high level spells the players will learn.
Learn new spells is hard. All spell casters have half (rounded up) number of learned or prepared. This will limited the possible of options in and outside of battle.
In exchange, learned spell casters can change any number of spells after a level up. Prepared spell casters can change any number of spells after short rest.
Do NOT completely remove cantrips. Cantrips is what separates spell casters from marshal. All spell casters start with 1 cantrip. Spell casters that start with 5 or more cantrips like sorcerer starts with 2 cantrips. They still learn new cantrips as they level up as normally. Subclass that grants new cantrips still starts or grants one cantrip.
In exchange, any classes or subclass lost cantrips this way, gain one skill proficiency regardless the number of cantrips lost.
D&D wiki, this website, has over 1,000 homebrew classes. There has to be classes that are similar to official spell caster classes that are not spell casters. If there is not a good alternative, there has to be a good marshal class to use. Only have 4 classes (barbarian, fighter, rouge, and monk) is too limiting.
Suggestion for a replacement for artificer: Tinkerling (5e Class) (a class that creates inventions with a slight magical ability)
Suggestion for a replacement for druid: Shifter (5e Class) (a class that has wild shape)
Suggestion for a replacement for paladin: Zealot (5e Class)
Research for spell-less classes
We live in a world full of information. Simply search up "D&D 5e spell-less ranger" or other spell casters. There is smart people out there whom have created wonderful spell-less classes. Even Wizards of the Coast, creator of D&D 5e, have experimented with spell-less ranger.
Another great class to search up is non-magic healer. D&D 5e is balanced around the fact that someone in your party can heal. Other than healer's feat and healing potions, there is no other ways officially to heal people.
Artificers are NOT spell casters in the normal sense. They do not cast spells from the magic weave. Instead they create inventions to mimic real spells. In a technological heavy world, inventions that mimic magic spells would be a perfect replacement for normal spell casters.
In a world with no magic, all spell casters should use inventions to mimic there cantrips.