A massive siege could be in favor or to the detriment of the party. Which side are they on?
A DnD Siege to Drop Into Your Game
These encounters contain information on how to run a DnD siege. Sieges can be complicated. When running them in 5e, I like to use some simple rules that reflect the scope and stakes of a massive battle, but keeps the action centered firmly on our party (and keeps combat from turning into an endless slog!).
We’ll keep things simple this week. The party is trying to capture or defend a keep, castle, or similar fortified area, at the center of the action (for our purposes, I’ll assume they’re attacking a small castle with some houses and a central keep, but it could be anything). For most of these encounters, I assume the party is an important part of a large army backing them up, but if you like a more high fantasy feel, or if your players enjoy feeling like powerful heroes, Encounter C makes them invaluable members of the charge, mowing down armies of enemies with the swarm rules!
Making a DnD Siege for your Game
Regardless of whether the party is attacking or defending, make sure you determine a few “key points” for the location. For our castle, I chose three: the main gate, the town square, and the keep’s entrance. Think about what location troops would have to move through—no matter how talented or powerful your party is, they need their army to hold this place!
For the castle, the main points of entry deeper and deeper would be the outer wall first. Once they’re in the small town, invaders have to keep access to the town square to effectively keep the roads under control. Finally, the main keep needs to fall, or the invaders will never call the castle their own.
Creating These Encounters
There’s a few reasons your players might take part in a siege like this one. Think about what the players are pursuing and the forces that might stand in their way, then choose an encounter from the list below that matches one or both.
Player Goals
- Gain a powerful base of operations, lair, or asset: Run Encounter A
- Prevent an enemy from gaining a powerful base of operations, lair, or asset: Run Encounter B
- Destroy an enemy army: Run Encounter C
Faction Goals
- Maintain control of a powerful base of operations, lair, or asset: Run Encounter A
- Seize a powerful base of operations, lair, or asset by force: Run Encounter B
- Raise a vast army and overrun the region: Run Encounter C
Rules
Sieges are simple: at each point, the party spearheads the most important battle while the armies rage around them. Combat runs as normal in each key point, but with a single main difference: on Initiative Count 20, losing ties, a player makes a skill check to command their troops. They can use any skill they like, as long as they haven’t used it to command their troops yet, but they have to justify to the GM how they can use such a skill effectively.
You’ll probably want to impose a stat restriction—once a character uses a skill rooted in one stat, no one else can for the rest of the fight. A fight probably won’t last more than six rounds, but if it somehow does, feel free to reset the cycle.
Set the DC however you like. For parties of level 11–15ish, I like to use a solid 20: tricky, but doable. Feel free to adjust it up and down depending on how outmatched the army is.
On a failure, the armies do poorly, and a slew of enemy soldiers enter the battle to fight the players. The specifics are up to you, but each encounter has a suggested number and type of enemies to keep things balanced.
Using DnD Siege Rules
I like to keep track of each stat by writing them down and checking them off each time one is used, so there aren’t repeats. You can use a character sheet for this, write them down on scratch paper, or ask a player to keep track of their own character sheet!
When the PCs are victorious, the siege is over! Their leadership can win the battle, but if they fail, their armies are without leadership and are reduced to a chaotic rabble and quickly defeated.
Encounter A
In this encounter, the party must lay siege to a mighty fortress, battling through armies.
How I Set Up This DnD Siege Encounter
This encounter involves using the siege rules from above to attack a castle. I used the three zones I listed earlier—main gate, town square, and keep entrance—to set up three smaller battles that bleed into one another as the characters race through the castle grounds.
I like to keep traveling between the zones as a time the players can take a quick breather. As they rush from the gate to the square, they can cast a few healing spells, quaff a potion or two, and so on. If you want a more intense, gritty siege, you can make every step forward a challenge by adding enemies or skill checks in between zones. This makes the fight much more difficult, so remember to keep the enemies weak.
Encounter Design
- Treasure Narration: Don’t be afraid to let the characters narrate how they command their troops. Let them feel powerful!
- Keep Scrope: Remember, the fight takes place over a large area, but narrate anything that isn’t directly related to the players without adding in extra rolls.
Action!
The party charges the gate! At each zone, there’s a different foe to fight. My party was fighting a duergar fortress, so I had them fight a ton of duergar appropriate to their level (you can find a great encounter difficulty generator here). For sieges, I like to set up a hard or even deadly encounter, then disperse the duergar across the different zones, with a few more in the last one than the other two.
Siege Rules
Command Check: At the start of every Round, a player rolls a command check (typically DC 20). Failure means a few more enemies engage them as they break through the troops.
For my group of four 12th-level characters, for example, I used 22 duergar. I put 10 in the final zone, then stuck 6 in the first zone and 6 in the second. Then the players fought through each one. As they marched between the key points, I gave them a moment to heal and prepare.Whenever my players failed a command check, I would add a few duergar into the fight depending on how poorly they rolled, usually somewhere in the neighborhood of 3. For more randomness, you could also just roll a d6.
How I Resolved This DnD Siege Encounter
When my players got to the final zone, they squared off against a ton of duergar and some cannons, and when they overcame the challenge, I had them describe how their commands let their armies overwhelm the enemies around them as they dealt the final blows to their duergar commanders, and they took the castle for their own!
They wanted to use the castle as staging grounds against their lich adversary, but let your group use it however they want! They worked hard for it, after all.
Encounter B
In this encounter, the party tries to defend a castle from huge waves of invaders.
Encounter Design
- Treasure Narration: Don’t be afraid to let the characters narrate how they command their troops. Let them feel powerful!
- Keep Scrope: Remember, the fight takes place over a large area, but narrate anything that isn’t directly related to the players without adding in extra rolls.
How I Set Up This DnD Siege Encounter
This encounter involves using the siege rules in reverse in which they need to defend the key points of their castle. You can keep using the three zones listed earlier—main gate, town square, and keep entrance—but this time, the players need to keep their key points safe, not conquer them.
Defending points is a bit of a different beast than trying to claim them. Remind your players they can retreat to a point further back at any time, and any time they do, give them a +5 bonus to their Command checks as they regroup.
The points are lost whenever the players have to retreat to a different key point, but they can always be reclaimed with another big fight.
Action!
Siege Rules
Command Check: At the start of every Round, a player rolls a command check (typically DC 20). Failure means a few more enemies engage them as they break through the troops.
For this encounter, I used demons, but it’s easy to substitute other enemies in. The encroaching horde is filled with bearded devils and imps, split up into three forces to attack the key points. This is a tough fight with lots of demons, but the group always has a chance to fall back to a previous point, no roll needed.
When a Command roll fails, I would throw in a couple of imps or a bearded devil. If the players are blazing through the encounter and you need an extra challenge, have something tougher like a barbed devil break through the front lines to engage the PCs.
How to Resolve This DnD Siege Encounter
The party fought through a few waves of demons, then I threw a barbed devil as a desperate final lunge. They fell back to the town square, but didn’t even have to resort to the keep.
When the final wave was through, the remaining demons were either killed or fled. They kept their castle, and the demons had lost a huge swath of their army.
Encounter C
In this encounter, the players must mow through massive waves of enemies, destroying a necromancer’s army.
Members Only
Encounter C is for members only. If you’d like to access it, we invite you to sign up now using this form. Membership is completely free and just takes a few seconds.
After you’re subscribed, you’ll be able to read members-only encounters all over the site. You’ll also receive weekly updates where we share more resources, our favorite TTRPG content that week, giveaways, contests, and more–all completely free.