Boss monsters are a hallmark of adventure design. The PCs gather clues and slay foes, working toward the ultimate villain. In the climactic battle, the PCs end the boss’s schemes and save the day.
Especially at lower levels, boss monsters can be dull. They are frequently guileless and lack interesting abilities beyond swinging their sword or commanding underlings to an early grave. Many bosses serve as a sack of hit points, doing a great disservice to villains everywhere.
So how do we fix boss monsters? We rebuild them into dynamic stat blocks.
The Sausage Making
Building a dynamic boss battle involves several steps. To make your own, here are the steps to follow:
1. Separate the monster’s attitude toward combat into three phases.
2. Break out the monster’s published stat block to match each phase.
3. Use or modify existing abilities that match the attitude for each phase. To improve boss effectiveness and survivability, add new reactions and bonus actions to make good use of the action economy.
4. Introduce lackeys with low hit points. Several full-blown allies can bog down combat, but lackeys (with roughly a quarter of the hit points that a standard monster of their type would have) provide an obstacle without slowing the tempo.
5. Add lair actions. A clever boss fights on their own terms. Even cornered, a boss monster chooses the battlefield, which grants them special actions on their turf.
Future articles will focus on different aspects of these boss fights. In this article we focus on developing the three phases of battle.
Duelist in the Biergarten
This boss is the shadow fey duelist from the Tome of Beasts. To generalize our boss, their race becomes Any Humanoid. To offset the loss of elven shadow fey features, the boss has four additional hit dice.
This duelist is the illegitimate child of a baron who has sufficient resources and charisma to operate their parent’s businesses. The duelist frequently wets their beak from related businesses in town, angering the other nobles who hire adventurers to quash the illicit activities. Assume that through the course of the adventure, the PCs have harried the duelist’s operations, finally cornering them in their biergarten lair.
The three phases of this boss monster represent the duelist’s evolving reaction to combat with the PCs: arrogant duelist, shrewd duelist, and evasive duelist. Different phases of the boss include reference to bandits (see SRD) and a bar brawl (see Creature Codex).
Normally, the duelist is a CR 6 monster, and many stats in the block are treated as such, despite phases being closer to CR 2. PCs who defeat the evasive duelist receive 2,300 XP.
Fight or Flight
Now cornered, the duelist searches for an escape route. Most features are based around moving after taking damage or slowing down pursuers.
Evasive Duelist (Phase 3)
Medium Humanoid (Any Race), Any Evil Alignment
Armor Class 16 (studded leather)
Hit Points 52 (8d8 + 16)
Speed 30 ft.
| STR | DEX | CON | INT | WIS | CHA |
| 13 (+1) | 18 (+4) | 14 (+2) | 13 (+1) | 12 (+1) | 15 (+2) |
Saving Throws Dex +7, Con +5, Wis +4, Cha +5
Skills Deception +5, Perception +4, Stealth +7
Senses passive Perception 14
Languages Common and two other languages
Challenge 2 (450 XP) Proficiency Bonus +3
Better Part of Valor. The duelist can take the Disengage or Dash action as a bonus action on each of its turns.
Nowhere to Run. When reduced to 0 hit points or fewer, the duelist begins dying.
ACTIONS
Multiattack. The duelist makes two rapier attacks. If it has a dagger drawn, it can also make one dagger attack.
Dagger. Melee or Ranged Weapon Attack: +6 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 6 (1d4 + 3) piercing damage, and a target creature must succeed on a DC 15 Constitution saving throw or become poisoned for 1 minute. A poisoned creature repeats the save at the end of each of its turns, ending the effect on a success.
Rapier. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 9 (1d8 + 4) piercing damage.
REACTIONS
Backflip. The duelist moves 15 ft. after being hit by a melee attack by an attacker they can see.
LEGENDARY ACTIONS
On initiative count 20 (losing ties), the duelist can take one of the following lair actions:
- Angry Throng. A swarm of inebriated allies (a bar brawl with 15 hp) join the fray, covering the duelist’s escape.
- Concealed Traps. One creature unwittingly triggers a hidden trap within the lair. This target creature must succeed at a DC 15 Dexterity save or suffer 2d6 damage, which can be bludgeoning, fire, piercing, poison, or slashing damage.
- Open The Floodgates. Burst barrels of spirits flood the lair. All creatures in a 30-foot cube must succeed at a DC 15 Dexterity saving throw or treat all movement as moving through difficult terrain.
Find the baseline creatures for shadow fey duelist in the original Tome of Beasts and the bar brawl in Creature Codex!
about Matt Dunn
Matt Dunn lives near Fredericksburg, Virginia with his wife and son, who he has written an adventure with. He works as a teacher, program manager, and part-time writer. Many of his outings have been with Eastman Dunn Press, who have written products for DMsGuild, Kobold Press, and Onyx Path Publishing.