How do you make an NPC villain to battle high level characters in 5e?

Question

I am building a campaign centered around the machinations of this one old elf wizard. I'm planning for the dramatic final encounter to be the PCs against him. The problem with this is that the PCs are going to be 15-17th level by the time they are up against him, and the maximum level for characters is 20th, which would be where he's at with the rules in 5e.

My only current idea is to create a few extra-powerful custom spells for him, but I'm not too sure how that will play out at all. I'm also curious how one would do the same for less magic driven classes, like fighters or rogues or whatever.

Answer 1

D&D 5e monster and villains are rarely, if ever, built like Characters, and this is actually a very good thing for you. That said, you need a starting point.

Start with the Archmage from the NPC Section of the DMG

It's easiest to work from a point that is close to your objective. The Archmage is a level 18 wizard (CR of 12). This is close to what you are looking for for a baseline, though you will likely have a lot of work to do to make him a challenge for the players.

In order to alter him properly to provide a challenge, you will want to look at several approaches.

Increase his level

Advancing him to a level 20 Archmage will not be too difficult in and of itself, but will only increase his CR by 1 or 2 points, so you will want to adjust fire from there.

Give him minions and guardians

Typically a creature that powerful will have loyal followers. Don't have him fight alone. Whether he has charmed an army of goblins to fight at his side, summons minions, hired a band of mercenaries, or simply has a loyal warrior that defends him, he will be highly benefited by having a few allies to keep his enemies away from him.

Make him tougher

In spite of the addition of allies, you can make him more resilient in several ways. Have him use clones or simalucra to make him stronger (via self-resurrection or duplication of his abilities). He can polymorph into something more dangerous, he can have spells that provide extra (temporary or real) hit points, or you can simply fudge it and give him more hit points. This won't address the next issue, but it is a start.

Give him extra spell slots of higher level (this can represent the scrolls I mentioned previously).

Make him Legendary

One of the biggest problems is that he will only act, by default, one to two times per turn. Since he is a boss, treat him as such. Those monsters in the MM that best reflect this are legendary monsters. Dragons, Liches, Beholders, Unicorns and more have both legendary actions and lair actions that can reflect an amazing boss encounter, and these can be used creatively to expand on what you have, making him formidable.

He doesn't have to follow PC rules, after all. I did this with a pirate captain, using his ship as his lair and giving it lair actions (that were basically things like the ship rocking from cannons going off, him tripping traps, etc). I also allowed him to do this through legendary actions for different types of traps, pitfalls, etc that he activated by 'pulling ropes' and 'flipping levers' in response to the player's actions. This made him seem like a master of his domain and added a lot of depth to the fight.

Ensure intimate knowledge of his skills

Have him use clones or simalucra to make him stronger (via self-resurrection or duplication of his abilities).

Pay attention to preparation spells... Especially if the wizard has access to decent abjuration spells. He should be prepared for the party... He should use scrolls to pre-buff for the fight, and Contingency to back him up. Hell, he likely has Wish in reserve. (Contingency on a teleport to get him out of Dodge when his hp gets low can frustrate the players, and make them have to face him again in another area of his domain, if you desire.)

Ensure you know what he is capable of... Should he be countering the party's spell-casters? (Counterspell as a legendary action/standard reaction would be particularly useful, but is easy to forget in the thick of battle.) Additionally, using Dispel Magic can cause the Wizard to debuff the party, thus taking away some of their edge.

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Ultimately, an unaltered, lone, level 20 wizard is unlikely to give much pause to a full group of level 15-17 adventurers, assuming they rush quickly in to battle due to low hp of wizards in general. A little preparation to keep the Wizard out of the front lines, and some special abilities can go a long way to make a memorable encounter.

With the above, I am not stating that you should add extra hp to the wizard. His minions, magical traps, and prepared spells may (and possibly should) be enough to make him formidable regardless. Build him how you need him to function, but ensure you keep a truly broad scope of what can be done to increase the potency of a major enemy. 5e has tons of ways to modify monsters based on the rules for them and your campaign's goals.

Answer 2

Does it have to be a physical altercation?

Common misconception is that the main villain has to be able to fight the party physically. This is simply not true and in my opinion comes from the video game mentality. You easily enough have the end villain be a child or physically weak individual with a few abilities that make him very influential.

Example villains from stories and movies:

1. Leader from Marvel Comics
2. Thulsa Doom from Conan the Barbarian 1982 (although in the book he was a competent fighter, his main henchman was far better, his power came from the zealots he influenced. Even the last "battle" wasn't with him.)
3. The Penguin from DC
4. There was a kid from the old Flash series from the 1980s that made toys.

What all of the above have in common is that they used minions and influence effectively to thwart the PCs and fled when the fight went against them. Recurring villains have that in common, they know when to run and fight another day.

NPCs can be built the same as PCs they just are not due to bookkeeping and preparation times. They have custom abilities that come close to class abilities the PCs would get but are more or less powerful and simplified for bookkeeping. Don't get too bogged down with the numbers in general and build the personality first. Write his abilities to balance against your desired CR from the DMG and flesh out abilities that enhance that personality and allowed him to get into that position of power and influence.

I would like to add that a commonly missed detail is that any treasure rolled for a monster/NPC intelligent enough to use it would be used by it. So if this is, in fact, a caster of some sort and their hoard included a wand, he would likely have it equipped and use it to maximum effect during any encounter. Barring any monologue of course.

Answer 3

First, always start with monster stat blocks when creating NPC opponents for the players. PCs are balanced around session after session of damage, with healing in between. Monsters are balanced around one fight, after which they are likely dead.

Second, (in my experience as a DM making many homebrew monsters) starting with a monster of approximately your desired CR, and then swapping things out and re-flavoring them is much easier than taking a more similar monster and leveling them up. Because it is sometimes hard to understand how adding a new feature will affect the CR of the monster.

For your situation, I would suggest starting with the Lich. It's CR21, and a spellcaster. You may need to change out stuff, but finding something that has a similar effect will help prevent changing the CR too much.

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As a final note: action economy is a cruel mistress. When your 3-5 PCs all gang up on 1 creature, it doesn't take much to bring it down. If each PC deals say, 30 DPR (about average for non-spell DPR with 75% chance to hit), then your PCs are dealing 90-150 DPR vs one monster. So if you want it to last 3+ rounds, it needs 300+ HP. More if you have spellcasters.

But, if your BBEG has 3-5 minions, then the PCs either have to take their hits to focus damage on the BBEG, or spend a round or two taking out the hired help before going after the BBEG. That will make your fight last longer without having to have a spellcaster with 300+ HP.

Answer 4

Minions and terrain.

As a DM, I much prefer to build my NPCs and BBGs by the same rules the characters have to abide by, and make the challenges stronger by having the bad guys act intelligently and with preparation.

If you set it up so that the characters have little choice but to take him in his lair, he can be well set up with pets and undead and Glyphs of Warding and Guards and Wards and all that. I also work to ensure that the bad guys have to figure out how to sustain themselves, that they can move about their own lairs (which limits traps), and all of that.

If the characters can figure out how then to lure the bad guy out of his lair, or lay siege and drive him out, then their job is much easier, and should be.

Answer 5

Sometimes what makes a villain stronger is just making him more intelligent. It technically has "omniscience" about the PCs, so use it for him. Make him target the fire draconic origin sorcerer with frost spells, employ hit and run attacks with minions to wear them down, or have him have a lieutenant that makes up for his flaws, such as a barbarian/fighter helper for your wizard evil guy.

Don't make him run up to the PCs and point blank shoot spells, or let them get close. If your villain is an old elf wizard, you can be damn sure the old guy will have his tricks up his sleeve and some neat uses for his magic, such as using shatter on the ceiling to drop it on your PCs, bombarding them with fireballs from above and making them go up a greased/poor condition staircase to get to him.

While making up spells to make up for some characters that could almost one-round-kill him, your PCs will/might want to know which spells he's using and feel bad that they don't have access to them. You could instead make a magic item to allow him to spam spells to keep up consistent damage (staff of fireballs/disintegrate, for example).