Wednesday, July 26, 2017

Boss Fights and Solo Monsters in 5e D&D

I've run a lot of 5e D&D at this point, so I feel confident in my anecdotal evidence when I make this statement: 5e isn't really built for party of adventurers vs. a single foe in combat. 

The reason why these fights don't work well in 5e D&D boils down to the "action economy"; a group of player characters will simply wear down a single foe because they have more actions (which equate to raw hit point damage and chances to inflict debilitating conditions) than their enemy (even if it has multiattack it likely can't output enough damage or debilitation on its own to keep up). Combat in D&D is essentially a war of attrition, so whoever has the upper hand in the action economy is going to grind down their opponent first--and when a party of adventurers has more actions to throw at a single foe, that beast doesn't really stand a chance.

I've got some ideas on how to even the scales to make for more exciting Big Fights, but first it's worthwhile to check to make sure that we aren't already tipping the balance toward disappointment by using a monster that isn't suitable as a boss. A "boss" or "solo" monster probably shouldn't be a "Medium" difficulty encounter according to the guidelines in the Dungeon Master's Guide. As the DMG defines it "A medium encounter usually has one or two scary moments for the players, but the characters should emerge victorious with no casualties. One or more of them might need to use healing resources" (82). In practice, it's highly unlikely that a party of adventurers will break a sweat in a medium combat, even against a like number of enemies, and you want your boss and solo fights to carry more weight than "they might need to use some healing resources." With that in mind, a boss or solo fight should start with a base difficulty of Hard or Deadly if you want it to have some dramatic impact and genuine struggle.

Now that we're clear on the base difficulty, we can consider modifying a creature to work better as a solo combatant. Consider adding a combination of the following to the creature's base stats:

Extra Hit Points: Since a solo monster has no minions to soak up damage, it will take every bit of damage the characters can toss its way. When I'm adding hit points to a boss monster, I tend to go with about 5 extra hit points per character for characters of 1st-4th level, 10 extra hit points per character for characters of 5th-9th level, 15 extra hit points per character for characters of 10th-14th level, and 20 extra hit points per character for characters of 15th-20th level. Those are just ballpark figures, you might use more or less depending on how many hit points the opponent has to start with. You want to add enough hit points to help the monster stay in the fight long enough to get its licks in, but you don't want to turn the fight into a grind.

Actions Outside Its Turn: The best solo opponents in the Monster Manual have Legendary Actions, a set of actions they can take in response to the players' turns in a round of combat. Adding these to monsters that weren't really intended as solo fights works really well in my experience. Personally, I like to use Legendary Actions as a way to add more color to a fight as well. For example, if a creature has a tail that it doesn't have a normal attack with, its fun to make a Legendary Action that lets it take a tail swipe in response to being attacked.

The Power of Nope: If you're adding Legendary Actions to a monster, you might also consider giving it Legendary Resistance as well: "If the monster fails a saving throw, it can choose to succeed instead." It's best to add this modification sparingly; at low levels, or in parties with few spellcasters, one or two instances of Legendary Resistance are fine. 

Bloodied Power: This is also a good place to steal one of 4e's better design elements--monster abilities that kick in once the players have reduced the beast to half its original hit points. Again, this is a place to add flavor--a fire elemental might get to drop a free fireball at half hit points, a giant might stomp the earth sending out a earth-rending tremor, a yuan-ti sorcerer might exude a miasma of poison, etc.

Better Defenses: You might also consider raising the creature's armor class and giving it bonuses to its saving throws, but in general this is my least favorite solution. In my experience it just tends to add more grind to combat and doesn't offer enough in return to make it worthwhile in most cases. If a monster has a naturally low armor class, though, it might be worth considered.

Let's put this all together and give an example of what a boss monster might look like:

Solo Basilisk
Size Medium, Type Monstrosity, Alignment Unaligned
AC 15 (Natural Armor), HP 72, Speed 30 ft.
STR 16, DEX 8, CON 15, INT 2, WIS 8, CHA 7
Senses Darkvision 60 Ft.

Passive Perception 9, CR 3


Petrifying Gaze: If a creature starts its turn within 30 ft. of the basilisk and the two of them can see each other, the basilisk can force the creature to make a DC 12 Constitution saving throw if the basilisk isn't Incapacitated. On a failed save, the creature magically begins to turn to stone and is Restrained. It must repeat the saving throw at the end of its next turn. On a success, the effect ends. On a failure, the creature is Petrified until freed by the Greater Restoration spell or other magic.
A creature that isn't surprised can avert its eyes to avoid the saving throw at the start of its turn. If it does so, it can't see the basilisk until the start of its next turn, when it can avert its eyes again. If it looks at the basilisk in the meantime, it must immediately make the save.
If the basilisk sees its reflection within 30 ft. of it in bright light, it mistakes itself for a rival and Targets itself with its gaze.

Miasma: When the basilisk is reduced to 36 or lower hit points, it immediately exudes a cloud of poisonous miasma. Any creature who starts their turn within 5' of the basilisk must make a successful DC 12 Constitution saving throw or become poisoned. This poison effect lasts for one minute, and an afflicted character can make a saving throw to end the condition at the end of their turn.

Bite: Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) piercing damage plus 7 (2d6) poison damage.

Legendary Actions
The basilisk can take 2 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The basilisk regains spent legendary actions at the start of its turn.

Claw: Melee Weapon Attack: +5 to hit, reach 5 ft. one target. Hit: 2d6+3 slashing damage.
Tail swipe: Melee Weapon Attack: +5 to hit, reach 10 ft. Hit: 2d4+3 bludgeoning damage and plus DC 12 Dexterity saving throw or be knocked prone.