Savage Species was one of the most popular, and disliked books of the 3e era, and the playable monster rules in the monster manual were honestly the foundation of why the system works as well as it does. A LOT of 3e or pathfinder players have not moved to 5e in large part because [insert pet race] isn’t a playable option. Even among those who do convert, it’s a common complaint. In 3e, I modify the playable monster rules a little bit, and have converted them for use in 5e.
Before diving in, 5e’s monster CR system is an afterthought at best (like literally, they released the monster manual and said they would define it in the DMG and shared preview rules they used for the MM. Then when the DMG came out, it had different CR rules after everyone laughed at the preview rules). This means these rules require a much heavier DM hand than I normally like to see. But if it lets me play a Frost Giant, it’s a sacrifice I’ll have to make. And let’s be real. If your DM is letting you use some guy’s house rule he published on his vanity site, you’re probably in a group open to a little bit of DM interpretation with your rules.
All monsters in the monster manual now have an Effective Character Level equal to their CR. If their CR is less than 1, their ECL is 0. A player character’s ECL is equal to their levels in classes. So a Mind Flayer, CR 7, is an ECL 7 character. In our system, a player can play a mind flayer with statistics taken straight from the monster manual as a level 7 character. If they wish to proceed in classes from this point, they are free to do so. When they gather enough XP to reach level 8, they can multiclass into a new class, provided they meet the prerequisites. They can then continue to level as normal. A note. You may run into monsters with ability scores of less than 5. They are not suitable for players, and are not eligible for this system. Unless you really really beg your DM.
ECL Guidelines Not Rules
Because there are so many monsters published, there is no way for this to work seamlessly. There are some exceptions that should be taken into account.We have put together 4 generalities that should be used to help ensure everyone has a fun time.
- The “No Dogs Allowed” Rule. You can’t play a monster that is 4 legged, has no arms, and can’t speak. If your choice of monster is closer to a dog than a human, you should pick something else.
- Hobgoblin: Obviously in. Bulette: Obviously out. Medusa: Pause, but sure that’s in. Blink Dog: Man this is a tough one. Ask your DM.
- The “My DM Hates Me” Rule. You can’t play a monster that your DM says you can’t. It seems kind of obvious, but it’s true. They might straight ban dragons as a choice. That happens, and you should pick something else. It’s a lot of work to plan for a monster PC, and there are some choices your DM may not be able to accommodate. Your DM may also decide to increase the ECL for a given monster choice arbitrarily. Maybe you’ve picked something with an ability that’s way out of line for a PC of your level (for example an arbitrarily large amount of hit points like the CR 4 lamia with 97 HP), and your DM will allow it, but only at an increased ECL. Or maybe you brought a veggie tray, and you’ve been told to stop bringing healthy stuff, so your DM straight out bans it.
- This rule has a counterpoint, the rarely seen “DM’s Favorite” rule. Sometimes your DM will decrease the ECL of a monster if you’ve picked something way underpowered. Or you bring good snacks, like anything with chocolate.
- The “Spellcasting is Hard” Rule. Some monsters get spells as though they were a traditional caster. Two things happen in this case. First, their ECL is set to their caster equivalent level or their CR, whichever is greater. Secondly, when you multiclass out and start trying to take real classes, you can enter your equivalent caster class at the next level allowed. So if your monster class casts as a 4th level wizard, you can start at wizard level 5, not level 1. Sometimes a monster does this, but won’t outright say it. Instead they list a big collection of spells, but don’t tell you what spellcasting class they are from. Your DM will have to use their best judgement to find the equivalent caster class and level to assign you.
- Trying to use this ability is probably going to queue up the My DM Hates Me Rule, and bring extra scrutiny to your character. This is a good thing, and a time for you to lay it all out in the open, so no one is surprised by your abilities, and the DM isn’t tempted to nerf you mid game.
- The “Pick a Real Race” Rule. Many monster entries are for things like Bandit (race any). They have powers that emulate class features, and aren’t really monster races. Pick a real race or class, and use that, these rules are not for that. They are for playing frost giants, not human bandits, who aren’t rogues. This also applies if you want to play something like a centaur. There is a playable centaur, and you should use that instead.