The northern Luzon giant cloud rat (Phloeomys pallidus) is a large species of rodent that is endemic to the Luzon Island of the Philippines. Cloud rats (genus Phloeomys) are distinguished from all other murid rodents by their densely furred tails. P. pallidus has long, dense coat that is highly variable in color and pattern. The coat is usually white with a black mask and collar, but can also be entirely white.
Context: So here’s the lay down. We’re playing a sea fairing campaign and we’re trying to obtain a ship. Our party includes a Minotaur fighter, a Psionic; who is keeping her identity a secret from the rest of the group, two dragonborn brothers a cleric (me), and a sorcerer. The sorcerer is a sharp tongued noble, the psionic has no patients for jokes and won’t hesitate to melt someone’s brain just for being obnoxious, i.e. the sorcerer.
DM: Okay so you form you party and are on your way to find the cause of disappearance of the town’s livestock. You arrive at the farm in question. There is a run down barn, a few small huts, and what appears to be a tool shed. What do you do?
Me: “I say we search the barn for clues.:
Sorcerer: “Okay let’s split up gang, you and the bovine go check the barn while our robed friend and I shack up in on of these huts!:
Psionic: "It is unwise to trust a robed stranger is it not?”
Fighter: “It’s also unwise to refer to me as a bovine, you ignorant lizard.”
Sorcerer: “It’s fiiiine i’m just joking around; however, hooded maiden the offer still stands.”
Me: “So to the barn then.”
We eventually figure out that their is a nest of giant rats who have been attacking the town’s livestock and stealing food and what not. The entire time the sorcerer continues badgering the Psionic, fast forwarding to the cave full of giant rats. Just got done with a fight everyone’s low on health and we’re about to rest.
Sorcerer: “This cave is a drag, why not head back to town and shack up in the inn? You can bunk with me love! (referring to the psionic)
Me: "For the love of Poseidon would you give it a rest! We have a job to do!”
Psionic IRL: Sorcerer, make a intelligence check.
Sorcerer, IRL: What? Why?!
Psionic IRL: I’m using Mind thrust, make a intelligence check.
Sorcerer: “No! Wait i’m sorry!”
DM: Roll, she already said it.
Sorcerer: *rolls* …. 1
Psionic: *rolls d10* I got a 10, how much health do you have?
Table looses it
DM: So yeah the sorcerer kinda grabs his head in agony and just slumps to the floor motionless. He’s dead.
Needless to say this is going to be a interesting campaign. I ended up using revivify on the sorcerer and continue our quest. All the while the sorcerer has been quite behaved since then.
The most straightforward method of increasing a low CR creature’s CR is by giving it class levels or by increasing it’s stats using the table in the back of the DMG. It’s a bit tedious, but it makes a more interesting creature once you are finished with it. No one expects the goblin with wizard levels or the kuo-toa with levels in monk!
More of them
Don’t do this one often, but you can always send a large number of low-CR monsters at the party. While adding class levels requires a lot of prep time, lots of monsters requires a lot of wasted in-game time, and that has potential to bore the players. But every once in a while, you can just send a whole bunch of monsters at them. When it doesn’t happen every single session, it’s a fun romp for the players to be able to feel powerful but still run the real risk of damage. Thanks to 5e’s bounded accuracy, more enemy attacks means more potential harm.
When players realize that the normally low-level encounter they are facing offers a lasting debuff attached to it, suddenly the encounter becomes more meaningful. They will have to take extra steps to avoid diseases, poisons, magical effects, or injury. For instance, a regular old giant rat is no threat at all at a pathetic CR of 1/8. But the locals have all been suffering from a plague carried by vermin, suddenly a bunch of rats has potential of ruining a PC’s entire day if they fail a save. Melee characters might opt to fight from range or spellcasters might need to burn a higher-than-normal spell slot to take them out quickly. A drow that drops a large creature with a small cut before going after the PCs suddenly becomes a hit away from poisoning a PC with who knows what sort of diabolical substance.
Environmental hazards can make advantages for enemies and disadvantages for the party which together can significantly alter an encounter’s CR. If kobolds are firing crossbows prone from high ground and have cover firing upon the PCs in an open area with plenty of traps hidden all over and a lava moat to find a way across, the PCs will take plenty of damage before ever reaching them. Even if they don’t take damage, they will likely waste valuable resources over a handful of kobolds. Carefully tailor your encounters in the enemies’ favor if they are a lower CR than the players, who will have to get lucky or clever to overcome the tipped scales.
There’s always a handful of abilities that you can throw at the PCs. Whether it’s the ones in the book (shoving, grappling, flanking) or ones you invent as a DM. Matt Colville once defending 4e D&D and its Powers for enemies. They always did something, and in terms of monsters they were occasionally unique to other editions of D&D. Try adding some unique abilities to your lower-level monsters that make sense for that creature. When I ran a game with an Aboleth, I heavily homebrewed some new abilities for it to surprise my players. I gave it a sort of Mind Blast (like a Mind Flayer) that would only knock creatures unconscious, making it easier to capture and enthrall players that got separated. I also gave it the ability to phase through ice as it was in a giant “aquarium” with ice walls, so it could either observe the PCs from its murky water or attack when it chose to reveal itself, or even drag a PC into the tank with it to coat it in its diseased mucous. Admittedly, an Aboleth is not a low-CR monster. But on its own, the PCs would have easily taken it out so I gave this guy plenty of advantages to tip the odds in its favor and the players still pulled through eventually. But I had made an easy encounter into a very challenging one.
Increasing the stakes of an encounter can alter how PCs approach a challenge. If players have to stay undetected, then even a bunch of orcs will be a threat to a party trying to sneak by a low-level monster, because it’s no longer about “can they kill it?” but “can they kill it before it has a chance to yell or else sneak by it?” Another option might be a requirement NOT to kill the creatures in an area. Maybe they are breaking into their own allies’ palace for information or to ‘borrow’ some magic item, but have no ill intent against the guards. Killing one might put them at massive fault. A time limit can increase the stakes of an encounter where they actually need to consider “should we waste time to kill these low-level creatures?” Perhaps those low-level creatures need to just be avoided instead so the players don’t spend too many precious rounds dealing with combat. There are plenty of other ways to increase the stakes of a battle, so get creative!
Saw a man refusing to let his pregnant wife off the porch because he “saw a rat the size of a dog and I will NOT let it bite you, please go back inside darling”. Made me wonder how protective the Maheswaran’s were of their baby.