Part 1

I don’t think I’ve ever met a DM that doesn’t enjoy homebrewing, and monsters are a typical homebrew concoction. Sometimes, however, you don’t want or need a brand-new, horrifying abomination dragged from the depths of your nightmares. Sometimes, what you need is a devil with a familiar face and a whole new bag of tricks. In those instances, punching up the monster’s level is the only way to go.
Why should you level up the bad guys?
There are lots of reasons why you might want to level up a monster instead of just picking a stronger creature from the monster manual. For instance, you might have an adventuring party that’s a little too strong. When the players rolled to find their ability scores, it’s possible they ended up with better than average stats. So the monsters you’re throwing at the adventurers just don’t offer enough of a challenge.
The CR system isn’t perfect either. The CR system is designed for a 4 player table and does not account for magic items. I can’t stress enough how relevant this is. I see a lot of angry rants about the CR system being useless. I understand the frustration, but I believe the root of the trouble is a misunderstanding of how to use these challenge ratings. But that’s a blog post for another time. For now, let’s say that the players have outgrown the monsters at their level. You’re going to need to power up the CR to match.
Finally, my favorite reason to level up the baddies, thematic continuity.
If the adventurers are on a quest against a certain type of villain, but that type isn’t strong enough to be a challenge, then they need some leveling up. Let’s look at some plot-driven reasons why you might want to power up the villains instead of just picking a different monster.
Power disparity between monsters of the same thematic type.

Skeletons are fun, but they don’t come in a lot of flavors. You have things like the Giant Skeletal Owl, Skeletal Warhorse, etc., but if your adventurers are running around an underground crypt, they probably won’t bump into those bony beasts. Having stronger skeletal soldiers, on the other hand, makes sense.
And of course, you may have a specific type of BBEG* and their minions need to match its style. I ran a campaign in which the adventurers were constantly harassed by a criminal organization. They eventually battled their way through the criminal underworld in an effort to, “clean up this city!” I quickly learned, however, that there isn’t a huge variety of criminals in the monster manual. My bandits and thugs needed to go to the gym and beef up.
So how do you build a level II thug?
First, you need to know why you’re building up your monsters. In my situation, I needed the criminal organization to keep up with my adventurers.
I hear you ask, “Why don’t you just throw more thugs at them?”
That is a good question, and this was one of the most important lessons I learned about homebrewing. This might even be the most important lesson I learned about being a DM.
Long battles suck! Short but threatening battles are exciting.
The DMG* is pretty clear on how action economy works. Of course, for the reasons already stated, you do have to get a little creative. When building your monsters, you need to keep in mind how many turns they get versus how many turns your players have. Sometimes a single battle can take up an entire session, but that shouldn’t be the norm. Most battles should end relatively quickly, but they should still be threatening. So you want your villains to pack a strong punch, but to go down within a reasonable number of rounds.

That’s why you don’t throw thirty thugs at a strong adventuring group. Yes, they’ll threaten your group because of the sheer number of turns they all get, but a powerful party might end up just knocking them down one right after the other.
Villains shouldn’t be bowling pins.
Instead, beef up the damage output considerably, and HP and/or AC moderately. Now you’re looking at a threatening enemy that won’t take four hours to kill. They may not go down in the first round, but they’ll get their ticket punched pretty quick. Excitement doesn’t come from long fights, it comes from dangerous fights.
Can’t we just give them better weapons?
Yep, and you probably should. Especially if you’re trying to catch up to a party that now has magic weapons. Action economy is calculated around levels, but there’s so much variety in what an adventurer can obtain over the course of a campaign. They could pick up a +1 sword, a potion of growth, some oil of sharpness, and now you have a living breathing death machine. Any thug with a thimbleful of common sense would ruin their underpants as the adventurers enter the room.
The CR ratings cannot account for that degree of complexity and variety, so test the waters. Instead of jumping right into a beefier build, give them a weapon with better damage output. I use the encounter chart in the Dungeon Masters Guide and through a “hard” encounter at the party. When the adventurers defeated the thugs without hardly any damage, I added longswords to my next Thug encounter. If the party could take down a group of longsword swinging thugs within 3 to 5 rounds and they took a moderate degree of damage, then the encounter would be quick and exciting.

Eventually, even thugs swinging long swords didn’t put much of a dent in the PCs hit points. The adventurers bought better armor, leveled up a few times, and ended up with some decent health regeneration. Potions, better healing spells, and magic items made writing up challenging encounters difficult with the standard array of criminals.
Keep an eye out for signs that your monsters need leveling.
There are a number of things you should look for to determine whether or not it’s time to level up your baddies. Sticking with the thug example, if the encounter ends after 1 to 2 rounds of what should be a “hard” encounter, your standard thug just isn’t cutting it. Another issue to watch out for is party members with high AC. If the paladin’s armor prevents threatening damage during battle, it’s time to punch up your villains.
I found that leveling up familiar antagonists accomplished a lot for my campaign. It allowed my story to unfold with a consistent theme and plot. I also managed to surprise the players. When familiar enemies are suddenly hitting harder, the adventurers take note. Again, if you need lots of lower-level monsters to challenge your adventures, your encounters will be a slow slog instead of an engaging experience. Leveling up your monsters is a fun way to reignite that excitement and sense of danger.
PS: I’m building a step-by-step guide on how to level up your monsters easily and correctly. My next post is going to dive into the nuts and bolts behind the mechanics. We’re going to walkthrough improving a stat block together. So check back in for Leveling up Your Monsters: Part 2.
BBEG: Big Bad Evil Guy. The primary antagonist in your game.
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I agree with all of this. For all of the complaining about CR that you see out there, there are just too many variables for it to ever be much more than a tool to give you a baseline.
I think leveling up your monsters makes a lot of sense. There are a lot of seasoned players out who know all of the creature books inside and out. Throwing a particularly nasty specimen at your party from time to time, keeps them on their toes, and that will ultimately lead to them having a better time at the table. Keep up the good work!