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Building Legendary Creatures in 5e

by Mike on 9 May 2016

Sometimes we DMs really love to throw a single powerful monster against our PCs. In the fifth edition of Dungeons and Dragons, these single powerful monsters are called "legendary" monsters. They have a special set of abilities that put them a step above the rank and file nasties in the Monster Manual. These effects are straight forward. Legendary monsters get legendary actions, legendary resistance, and, in some cases, lair actions.

Today we're going to look at a simple method for turning any monster into a legendary monster that will shake the resolve of the PCs and give the players a thrill.

The Basics: Legendary Actions and Legendary Resistances

There are some easy mechanics we can throw right on any monster to make it "legendary". The first, and easiest, is legendary resistances. Legendary resistance can be found in any listing of a legendary monster in the Monster Manual. Here's a summary:

Legendary Resistance (3/Day). If the monster fails a saving throw, it can choose to succeed instead.

This is a simple but powerful ability. It essentially removes any save or suck effect from ruining the legendary monster's ability to threaten the PCs. This can be a frustrating ability, though, so you'll likely want to give players a hint that their big save or suck ability isn't likely to affect this monster. More on this later.

Legendary actions are a little more difficult to figure out. Stock legendary monsters usually have a set of special abilities designed for legendary actions but our custom legendary monster will not. Here's the boilerplate for legendary actions:

The legendary monster can take 3 legendary actions. Only one legendary action option can be used at a time and only at the end of another creature's turn. The legendary monster regains spent legendary actions at the start of its turn.

The easiest way to handle this is to give your monster an extra attack as its legendary action. Some monsters might have other abilities you can substitute in as legendary actions. You'll have to gauge the power of these abilities to see if they deserve one, two, or three points to activate.

In general, the easiest way to handle it is to give the legendary creature an extra single melee or ranged attack for one legendary action.

Tweaking Hit Points

Now our legendary monster has some better defenses against save or suck effects and more actions per turn than your standard beast. What else should we tweak?

Generally speaking, we shouldn't have to mess with attack scores or its armor class. If it fits the monster, you can tweak attributes a little bit but that is probably more troublesome than its worth.

Instead, focus on hit points. This is a much bigger version of that standard monster you're changing and bigger monsters have more hit points. There are two ways to do this.

First, consider maxing out the creature's hit points rather than using the average. This is easy to do in the middle of your game. Look at the monster's hit dice, multiply the dice by the max amount on each die, and add any hit point modifier to it.

There's another easier way to handle this as well and that's to double the monster's hit points. This puts the monster outside of the normal range any version of that monster should have, but it won't be too far off. Maxing hit points is certainly more accurate but doubling is easier to do and will make that legendary creature even more challenging.

Flavoring Your Legendary Monster

As it stands, giving monsters more hit points, legendary resistance, and legendary actions is pretty boring. Sure, it's a big version of a monster, but why?

Flavor is what will bring this terrible creation to life. What makes them so powerful? Have they been touched by a dark god? Are they the spawn of a demon lord? Are they infused with the glyphs of a powerful wizard? Think about what makes this legendary monster so powerful.

Legendary Identification

Should you let your players know they're facing a legendary creature? Should they know what it means if they do? Different DMs will have different opinions on this. I lean towards the 13th Age style of "play in the open". You don't have to break the narrative to give them a peek behind the curtain:

"Grash, the legendary nether-touched orc lord stands before you. You feel deep down that this foe possesses great strength and resolve."

As we mentioned earlier, legendary resistance can really frustrate players if they blow a powerful save-or-suck spell like dominate monster or banishment on a legendary creature only to have it fail. Sure, it knocks one use of legendary resistance away, but they'll have to hit it with two more of those before they have a chance at landing a spell. Usually its better to give the player a clue that their save-or-suck spell isn't likely to affect such a legendary foe.

So yes, much like how Fallout 4 places a star next to a legendary monster's name, we too can give our players a clear indication that the foe they face is clearly a legendary foe and should be treated as such.

No Monster Fights Alone

Because our legendary monster feels so powerful, we're tempted to have it fight a single group as a solo monster. Even though our monster has legendary resistances, however, doesn't mean something won't completely paralyze it. Force cage, for example, could still trap it. All creatures, including legendaries, could probably use some help. What minions and bodyguards does this legendary foe have with it? In some cases, these bodyguards can end up more dangerous than the legendary creature itself.

When building an encounter around a legendary version of the creature, it's best to treat it as two creatures at the same challenge level. If you're designing an encounter around four CR 5 creatures and want to make them legendary, have the legendary creature count as two.

Tying Into Out of the Abyss

The Dungeons and Dragons super-adventure Out of the Abyss is a great place to drop in some legendary monsters. The corruption of the abyss into the underdark could have twisted many powerful foes into legendary champions of any particular demon prince. This corruption is a great opportunity to flavor a legendary monster. Here's an example:

Grash, the Legendary Gnoll Fang of Yeenoghu

There's one really powerful effect we can add to a legendary abyssal-touched creature in Out of the Abyss: madness. At some point in the battle, the legendary abyssal creature may put an abyssal eye onto a target, invoking a madness in its opponent. The targeted creature must make a charisma saving throw with a DC somewhere between 12 and 15. You can calculate this saving throw if you want using the rules in the [Monster Manual] or just wing it. Generally DC 12 to DC 15 is right. On a failure, the creature succumbs to short-term madness found on page 259 of the Dungeon Master's Guide. These are really powerful effects, however, so be careful.

Risk for Reward: Adding Treasure to Legendary Monsters

Powerful monsters should have powerful loot. There are a couple of ways to add some good rewards to a legendary monster. The first is to give it a CR appropriate treasure horde, re-rolling on the table if no permanent magic items happen to show up. A second way is to roll ahead of time and pick out and flavor some interesting items to arm your legendary creature so it might get a chance to use them against the PCs in the fight.

You can also use K. Walter's random treasure generator to run a bunch of parcels and then pick the one you'd like to affix to your legendary monster.

Of course, you can always hand-pick some interesting loot to award to players based on items that fit their characters. That's usually the hardest to improvise but is often worth the effort given how much joy it gives to the player.

A Quick Way to Add Some Flavor

Throwing some legendary monsters into your game is a great way to shake things up. Players won't be expecting it and everyone enjoys some added challenge now and again. Give it a try.