Figuring Out Combat in 5e: Monster Longevity
This is the second part in a multipart series focusing on combat in 5e and how you, as the GM, can adjust it to better fit your table and needs. The first part, Hitting Your Players, is all about how to better hit your high level or high AC characters while not overinflating the damage. This post is about what happens when your players mow through monsters like an angry chainsaw through wet tissues.
When I flip through our beautiful monster manual and choose what creatures will grace my table next, I can be a bit disheartened when I see that certain creatures, that have a high CR, have so little health. I find it frustrating that these massive CR creatures may get knocked out in 1 round if they roll poorly for initiative.
Come At Me
Let’s take an extreme example of this and grab our best buddy, the Lich, a CR 21 creature that should be a difficult challenge no matter who you are. But… this is an example of a creature that will have a bad day if they get a 1 on their Initiative roll. They only have 135 HP with a 17 AC. Their defenses are awful and their regular attack, Paralyzing Touch is going to be pretty much useless when fighting your players. Now, Liches are going to focus on their spells, and the default spell list for Liches aren’t going to get you very far in a fight, especially having two utility cantrips.
With that said, you can always change out their spells they have on hand, you can always give them a Staff of the Magi to supplement their spells and you can give them a few other magic items to strengthen up their AC or Spell Save DC. But all of those changes are going to affect how difficult and powerful they are. This will change their CR rating and you may inadvertently make your Lich too powerful for your party. Most changes to a monster have this unattended side effect, when all you really want to do is make your Lich last more than a round against your players.
Just Gotta Hold On
Now lets get to the real meat of our problem here. We have a group of powerful players that deal out an insane amount of damage at higher levels. We already know that the Lich will die at the hands of the party, since it’s kind of integral to our plot. The players will live and your BBEG will suffer a defeat, most likely a defeat of dying. But we love our BBEGs. Part of the fun of this game is that we get to have all these different monsters with crazy abilities. That is all for not when your party strolls in, gets the initiative in their favor and they completely steamroll your boss in one round before he has a chance to do anything.
And a Lich is very likely to get steamrolled if your players catch him off guard and in a tight space. With only 135 HP, he has the same amount of health as an Aboleth, a CR 10 monster with the same 17 AC. Beyond having a ton of spells at the Lich's disposal, a lich also has immunity to non-magical weapon attacks. But by the time your players are facing a lich, it’s likely that most, if not all, your party has the ability to have magical weapon attacks (or they don’t even use weapons as their main form of damage). By 6th level a Circle of the Moon Druid already has magical weapon attacks, so that ability does very little for our Lich but make him a threat to peasants and a non-magical army.
Living Longer, Its Good For Your Health
Now, all I’ve been doing is griping about the Lich and how it is weak and won’t survive very long in combat if several factors are going against it. I’ll admit, I’m looking at worst case scenario for your Lich, but this can be for any monster you have. Sometimes your players are great at chewing through monsters and you just want your monster to live just one more round so you can use that breath weapon again or that really neat spell that will totally kill that one annoying cleric.
To accomplish this, let’s look a little closer at our Lich, he has 135 HP, but that isn’t the whole picture! Our Lich actually has 135 (18d8+54) Hit Points. This means that the average Lich will have 135 HP, not ALL Liches will have 135 HPs. Now, I’m not telling you to roll for the Lich's health, but rather to figure out the Minimum and the Maximum for all Liches.
We are going to times the 18 (number of hit dice) by two different values of the d8 (hit dice size), the minimum (1) and the maximum (8). This, plus the medium health of the Lich, will give us a range to work with for our Lich.
18 * 1 + 54 = 72 hit points, maybe this Lich is still young and you want a chance to showcase differently powered Liches in your campaign
18 * 8 + 54 = 198 hit points, this will give a single Lich a much greater chance of surviving a round or two of combat
So taking our three numbers 72 | 135 | 198 this will give us a range of health our Lich could have and will allow you to alter combat as you need to. If you players are always hitting above their weight class, you can throw in a Lich with 198 HP. This allows the Lich to live for more than a single round and truly lets the players know how fearsome their opponent is. Or maybe your group doesn’t even like combat and is just here for the story and roleplay, then you can put in a Lich with only 72 HP. This allows the players to still kill the Lich without feeling like they have to slog through combat.
Using HP in this way still keeps a Lich at their original CR rating and doesn’t make them any more powerful than before. What it allows them to have is staying power, they no longer are cut through like wet tissue and can go down when the GM feels it is appropriate for their party. It gives you customization of any monster from CR 0 to CR 30 to better fir your table and the story you are telling.
I use this to help my monsters out all the time. Sometimes a combat shouldn’t rely on just the average of the monsters and by learning the ranges of hit points for your monsters, you can give certain creatures more flavor than others. If one of the monsters has taken way more abuse than the others, but is still walking around… well your players will take notice of it and realize that that one was the big boss and the others merely it’s servants. Plus… next round I may get to use my breath attack again, and it’s so much fun rolling all those dice.