D&D 5E Ballista War Wagon

[ElterAgo]

So I'm the GM for a rather eclectic group.

They had originally bought a cart just to haul a single bulky item for a couple of weeks. Then they purchased a ballista to mount in the cart to make it look like a major attack on a manor for a distraction (it never actually happened). Somehow this has unexpectedly become a major plot item for the group. They want to add things and make modifications to the wagon. Want a secret compartment large enough to hold a body. Protections on the wagon to resist fire. A swivel mount for the ballista. Wheels/axles that won't break all the time. Wheels that can travel through swamps/forest/snow? Shield walls to protect the cart wheels, driver, or gunner. Special ballista bolts to fire grapples, a bundle of alchemists fire, nets, harpoons to grab someone, etc...

Has anyone ever seen or made up rules for this kind of thing? How much should these kind of modifications cost? What skills or rules for using a ballista to attack a giant? If a war wagon starts getting hit with spells, how much damage can it handle? This sort of thing hasn't come up for me before this in 5E.

 

[Oofta]

Umm, all of that is quite ... creative.

The problem is there are no hard and fast rules for crafting custom items. The best you can do is reference the DMG and look at Chapter 6: Between Adventures > Downtime Activities > Crafting a Magic Item. Cross reference that with Chapter 9: Dungeon Master's Workshop > Creating a Magic Item.

So for example for the wheels to work on water I'd consider that Boots of Water Walking, except applied to the wheels. Since the wheels are now magic, they're quite hard to break. There are rings of fire resistance and so on.

Armor? I'd look over at barding, but consider making it for a huge huge creature instead of large so it's more than X4 cost. The other stuff? If you have Ghosts of Saltmarsh you can always look at the appendix Of Ships and the Sea which gives some info, they recommend 15,000 GP and 1d4 weeks of work per upgrade which includes Grasping Rounds, the target must succeed a DC 14 Strength saving throw or it can't move away and it's a DC 14 to break the grapple.

There may be something else out there, I've always just kind of winged it. Then again nobody ever asked to build a battle wagon. I googled D&D 5E hardness and found this link. Hope that helps!

 

[aco175]

Ask the players how much they think these things should cost. Have some adventure finding people that can enchant or craft these things. This may lead to other adventure with finding something specific like red dragon skin for the fire protecting armor or such.

 

[ElterAgo]

I did ask what they thought was an appropriate price. All I got was a shoulder shrug "never done anything like that before."

I do like the idea of dragon hide armor on the sides.

Oh yes, it is very creative. It is a wonderful problem to have as a GM. I like the idea of the boots of water walking for the wheels. That will work fine. Same with ring of fire resistance.

Barding price seems a bit high, but I will consider.

I will see if one of the guys has Ghosts of Saltmarsh.

What do you think about a secret compartment in the floor?

 

[Uni-the-Unicorn!]

So I'm the GM for a rather eclectic group.

They had originally bought a cart just to haul a single bulky item for a couple of weeks. Then they purchased a ballista to mount in the cart to make it look like a major attack on a manor for a distraction (it never actually happened). Somehow this has unexpectedly become a major plot item for the group. They want to add things and make modifications to the wagon. Want a secret compartment large enough to hold a body. Protections on the wagon to resist fire. A swivel mount for the ballista. Wheels/axles that won't break all the time. Wheels that can travel through swamps/forest/snow? Shield walls to protect the cart wheels, driver, or gunner. Special ballista bolts to fire grapples, a bundle of alchemists fire, nets, harpoons to grab someone, etc...

Has anyone ever seen or made up rules for this kind of thing? How much should these kind of modifications cost? What skills or rules for using a ballista to attack a giant? If a war wagon starts getting hit with spells, how much damage can it handle? This sort of thing hasn't come up for me before this in 5E.

For the cart stays I would look at some of the vehicle rules. It should have AC and hit points and maybe a damage threshold and probably a cost that should give a baseline to go with. There might already be rules for ballista as well.

 

[Hawk Diesel]

Sounds like they want a mobile stronghold. That might be a good place to start. Think of it like that rather than a cart. Matt Colville has some really good rules guiding the creation and maintenance of a stronghold in Strongholds and Followers.

 

[dave2008]

I haven't looked at them, but the War Machines from Descent into Avernus might be a good place to look for ideas.

 

[Benjamin Olson]

One of my groups totally became fixated on our wagon. Pimping said ride became the ongoing downtime activity of the artificer. But the costs and effects on the stats of the thing were negotiated between him and the DM on an ad hoc basis, so I can't really give you much insight.

 

[dave2008]

Here are the rules for the Infernal War Machine. It seems like a good place to start to me. However, I have no idea about the cost of doing this. Also:

War Machine Handout
Infernal War Machine Preview

 

[Hawk Diesel]

Yea, the infernal war machines are another good place to get inspiration. Good call @dave2008