In the right situation, enemy spellcasters can be extremely dangerous. They have access to powerful spells and abilities that can inflict grievous damage or disruption to the player characters. Some of these are BBEGs, but many are simple "encounter bosses", typically found in the final of that evil cultist shrine, or what have you.
Note that for the purposes of this article I am referring to the traditional spell casting enemies, like wizards, sorcerers, shamans, warlocks, priests, etc. An ancient green dragon, while technically a spellcaster, is not something that I would suggest beefing up due to the fact that they are very tanky and require quite a feat to overpower in combat.
The problem with these fantastic specimens is that they generally have some piss-poor defensive stats. They usually have a low hit point pool, a pretty low armour class, and usually some susceptibility to saving throw failures as well. When coupled with the fact that players see these encounter leaders with the word "BOSS" tattooed on their chest, their defensive statistics don't hold up too well when the party inevitably focuses their fire and throws their resources at taking these down as soon as possible.
Since this, let's call it, "natural selection" of players targeting anything that looks like it can do cool stuff (or dangerous stuff), is a thing, we may as well try to look at ways to utilise these enemies better. The best solution isn't just to stat-pad the wizard with more HP and a higher armour class. He'll start to feel just like a bugbear again and we're back to boring old square one; hence why I use the term "utilise" as opposed to "make them stronger".
So let's have a think about some ways that a spellcaster can utilise their power more effectively in combat.
Wizards (and most other spellcasters) are likely to have high wisdom, intelligence, or both. Yes, this is included in their spell bonuses, but remember that their thought processes would also be influenced by this too - they aren’t idiots! So we need to factor this in when thinking about ways they can utilise themselves more in combat. We need to remember that squishy spellcasters are usually very aware that they are a) squishy and b) a spellcaster. They wouldn't just charge into the fray.
To start, let's look at the biggest downfalls that these spellcasters have. Let's look at some reasons why they aren't as challenging as they perhaps might otherwise be:
1) They get focused on with big spells/nukes and martial heroes’ attacks;
2) They are often the juicy target for any of those "disruptive" spells the PC casters have such as Silence, Blindness, Confusion, Charm, etc.;
3) Their armour class and hit points are usually low, for their challenge rating; and
4) They don't function as effectively when adjacent to the hostile PCs.
I have a few potential solutions to this:
1) Don’t start combat with the caster in danger
Don't start the caster in the room when the fight breaks out. Have him enter part-way through instead. Let's say the PCs kick down the door of the wizard's quarters. What happens? Maybe his well-trained mimic treasure chest attacks! Perhaps the two suits of armour against the wall come alive and attack. Then have the wizard enter from an adjacent room on the following round, or even a few rounds later.
Alternatively, when the party attacks the wizard's guards in the great hall, the wizard hears the commotion (or an alarm spell is triggered) in the main chamber, and he enters with his golems and joins the fight mid-way while the players are already occupied.
The first advantage to this is that the wizard avoids the snowball of death that is the opening round of a D&D combat; where the players use their strongest abilities and try to burst down any immediate threats as quickly as possible. If the wizard walks in on a later round, it throws a spanner in the works by creating a tactical challenge for the players! Also, if the wizard has a round or two before they enter combat, they can cast those juicy defensive spells before they even step into the danger zone. Spells like Mirror Image, Mage Armour, Armour of Agathys, Blur, etc. are great.
2) Cast Invisibility/Blink
Have the wizard in the area, but have them unseen (due to Invisibility) or in another plane (with Blink). Until the wizard attacks, or is revealed, Invisibility will shield them from a lot of unwanted aggression from the PCs. Blink is a good disruptive defensive spell, as it will give the caster some rounds without any danger from the players.
3) Illusion Shenanigans
I've done this a few times and it's worked out pretty well. Just try not to be too mean with it, and don't overuse it.
There are a few ways to use illusion shenanigans. Firstly, to obscure the wizard from view (have a bookcase or some other Line of Sight blocker in between the party and the wizard's.) If the illusion goes, the wizard is revealed! Alternatively, disguise the wizard so that he looks like a commoner, a prisoner, or perhaps a grunt in the combat. Thirdly, you can disguise one of the other enemies to LOOK like the wizard with an illusion spell.
In one of my campaigns, the illusionist wizard was in a large chamber with a bunch of his golems. The paladin of the party, who hated him, ran forward and used misty step to be right next to the wizard, and then attacked. It was then he realised that the wizard's image was only an illusion, cloaking the real enemy - the wizard's champion battle golem! The paladin was alone, right next to it! You could also use illusions as 1hp minions to try and coax out spells from the players. Use this approach in moderation, as it can backfire in nasty ways, i.e. players running amok in revenge.
4) Run two wizards
You can't focus fire two things at once! Another option is to consider running two, slightly weaker wizards as opposed to just one. (Or 3 wizards, or 4, 10, 20, etc.) Sure, one might get focused down and annihilated, but the other will still be up! Or your party might panic and half-kill both of them, leaving them both free to wreak havoc on their next turn!
5) The Old Switcheroo
The party kicks down the door to see an evil warlock in robes completing his ritual. He is surrounded by 4 demonic brutes, and he glares at you and gestures with his finger, pointing for his demons to attack the intruders. The players think "Oh crap, we gotta kill that warlock first so that the encounter is easier." But what they don't know, is that the warlock is just Joe Bloggs from Villagehills down the road, who turned a dark path and read the wrong page from the black tome. He has AC10, no spells, and one hit die. The real threat of this combat are the demonic brutes, but I can bet money that some useful spells might be wasted on this commoner - spells which really would have been more helpful if used on the demons. Again, don't overuse it, but dab it in your world here and there for a bit of fun.
6) Use The Battlefield To Their Advantage
Design encounters that really suit wizards. Throw in a lot of inhibiting terrain that slows movement or forces the players to take a long route to get to the wizard. Having a ravine or crevasse in-between the wizard and the party is an easy way of doing this. You could also accommodate this with a trap (like swinging axes) that stands between the players and the wizard's (But you should think of offering a long way around the trap for players who don't want to tangle with it). Also, of course, remember to station the wizard's allies as a barrier between the wizard and the PCs.
There are two types of DMs in the world. Those who increase difficulty by giving their spellcasters more hit points and a higher armour class, or those who use more strategic or creative measures to increase the challenge. Harder doesn’t necessarily mean more hit points. Use the above to really let those players know how crazy powerful spellcasters can be!
Peter is an avid dungeon master, role-player, and story teller. When he's not running homebrew campaigns, he is creating new worlds, or he is reading and writing fantasy stories, forever immersing himself in the gaping black-hole known as the fantasy genre.
Image Credit: http://vignette3.wikia.nocookie.net/uncle-grandpa/images/2/27/Transparent_Evil_Wizard.png/revision/latest?cb=20140515001325
I am become death, destroyer of worlds.