Your players have reached level five - or maybe higher. They have access to stronger spells, can attack twice per turn, and have already found magical gear. It’s not yet time to hit them with the hardest monstersDungeons & Dragonscan offer, of course, but you can hit them a bit harder. It’s time to remove the training wheels.
These levels can be a complicated challenge in terms of balance for that specific reason - you can (and should) use stronger tactics on them, but not the strongest ones just yet. What features, attacks, and spells can you give to such a creature, then?

We also have a list forlow-level bosses- don’t be afraid to mix the abilities there with some we added here to create the ultimate mid-level boss!
10Stronger Resistances Or Immunities
Adapt To The Party
By now, your martials already have magical weapons to bypass the class resistance to bludgeoning, slashing, and piercing damage from nonmagical sources, so it’s time to focus on other damage types.
You could add resistance to one of these even if the weapon is magical, but the thing you should focus on is the spellcasters, as they’ll hit harder from now on. You can choose a damage type that makes sense to your monster - or one your players use a lot - and just give your monster resistance to it.

You could also give them damage immunity, but be careful not to exaggerate on those - only one is enough, and it depends on whether you’re closer to high levels than low levels.
You can also add Magical Resistance - an advantage on saving throws against magic - to help your monster take half the damage in most scenarios.

9Condition Immunities
Also Adapt To The Party
Speaking of immunities, this is an excellent time to consider making your bosses immune to certain conditions rather than just damage. For instance, if a group successfully uses Hold Person on your monster, a paladin can destroy them in two smite-fueled strikes. Perhaps immunity from being paralyzed would be helpful here.
Again, it’s still early to stack a bunch of those already, but making the boss immune to one or two conditions won’t be the end of the world, especially if these are conditions your players often use, because now you’ll force them to think outside the box and try different strategies.

8Teleportation
Avoid Opportunity Attacks
Teleportation is a good way to threaten a whole group of players is the power to move freely throughout the battlefield. You can immediately hit squishy targets with melee attacks or go to safe places to avoid melee attacks yourself while attacking from afar, among other things.
you may even turn your teleportation into a Legendary Action to use it more often, giving you a better action economy and making it a core feature of your character rather than a spell, preventing Counterspells against your teleportation.

7Flight
Become The Master Of Positioning
Flying is also a good trick to use on the battlefield. Though it won’t necessarily save you from opportunity attacks, this is a beautiful way to keep your distance, making life extremely hard for melee characters, or even grapple and drop them while in the air just for fun.
That said, you’re also opening yourself to being immobilized, trip attacked, or similar, and your players will feel very satisfied if they manage to drop the creature and cause them some extra fall damage.

You can also create a Legendary Action that allows you to move half or all your speed without causing opportunity attacks for extra maneuverability.
6Legendary Action Attacks
The More Attacks You Can Make, The Better
We have mentioned legendary actions a few times now, which essentially give you the ability to use one of your features outside your action. While it’s still too early to go overboard with legendary actions, one simple thing you can do is let your boss make an additional attack with one of them.
That way, your monster can cause three more attacks, all outside their turn, significantly raising their danger level. You could also give them the option of casting a spell this way, but we advise using that for either a cantrip or a low-level spell that targets one enemy only.

As a quick note, we also recommend adding a secondary damage type to the enemies' attacks, like an extra d8 necrotic damage. You could even give your boss access to Divine Smite, as long as it fits the character!
5Regeneration
Make Your Monster More Resistant
At the start of your turn, you recover hit points. That’s it. It’s a trick creatures like Vampires can pull off, and as long as you don’t forget about it, it’s a very helpful trick to have if you want to make your monster more durable.
The number of healed hit points depends on the size of the health bar, as it can’t be too low to the point that it is useless or so high that it is overpowered. Just make sure to narrate that the monster’s wounds are closing or something similar, as it can be countered by something as simple as the Chill Touch cantrip, making things rather balanced.

4Life Steal
Optimize Offense And Defense
Whether you want to use a spell, likeVampiric Touch,a legendary action like the Aboleth’s Psychic Drain, or homebrew something of your own, the idea of converting damage you cause into hit points for your monsters is very effective.
You can create something that steals health from stunned characters or a similar condition or an attack that causes a secondary damage roll that also heals when hit. We don’t recommend anything that heals too much, depending on how easy it is to activate (like every successful hit).

3Anti-Healing Strikes
The Healer’s Nightmare
Taking a page from the Mummy Lord’s stat block, let’s talk about attacks that prevent the character from recovering hit points. The Mummy Lord’s version is a bit intense, so you can control the power here by deciding how easy it is for the enemy to activate it (similar to the life steal trick above) or by how long the anti-healing lasts.
You can do something similar to Chill Touch - a simple attack that activates anti-healing for a round - or something stronger, like a recharge ability that prevents the target from healing until they rest.

2Nonmagical Area Of Effects
Hit The Ground Or Breathe Fire, Or Something
While spells are an effective thing to have - and we’ll discuss them shortly - your players are now reaching levels where they can counter your spells with theirs. Thus,a recharge abilitythat hits multiple people is useful.
This way, you can be efficient with your action economy by hurting an entire group at once while avoiding the chance of being annulled and losing your action in the process. You can control how powerful it is through damage, range, and whether it’ll hurt your monster’s allies, too.
1Spells
Counterspell Enters The Chat
You can hit a lot harder with spells now. From classics like Counterspell and Dispel Magic but also area spells, spells with stronger effects or extreme single-target damage, since revivification is possible now.
As for spells that can be used more often, the range between third to fifth or sixth-level spells can give plenty of options that are easier to spam, like hitting the group with a few Fireballs. You should also think of spells that weaken them or boost yourself in the process.
Dominate Person, Polymorph, Mass Suggestion,
Damage
Fireball, Sickening Radiance, Cone of Cold, Wall of Fire, Chain Lightning, Call Lightning