Tuesday, July 15, 2014

Fire in the Hole

I have a few nitpicks about the spells in the 5e Basic rules.  Sleep only lasts a minute, Charm Person last only an hour.  Revivy, basically a combat time Raise Dead, is only a third level spell.  Fireball and Lightning Bolt are no longer d6 damage per caster level.  There are other things in the spell section I could get worked up about.
Instead, I’m going to talk about something I like: the return of the dangerous Fireball.  Ditching the skirmish-minis friendly burst template of 3.x (I honestly have no clue how Fireball worked in 4), instead we’re back to the golden era of the Fireball that forms a 20’ radius sphere of blazing death.  The implications of this change are enormous for dungeoneering play.
Feel free to check my math with Wolfram Alpha or look up how to calculate the volume of a sphere on wikipedia (if you know the formula, give yourself a math nerd point), but my calculations indicate that a 20’ sphere has a total volume of 33,510 cubic feet.  In short, a Fireball loosed into a dungeon environment expands to ignite targets in 33½ cubes of 10’ by 10’ by 10’.
That’s a helluva lotta dungeon, my friends.  Using this volume calculation for most of the 30+ years I’ve been DMing has resulted in more toasted party members than I can count, and more than one magic-user self-immolation.  Hell, I roasted myself at least once back in the eighties, and I don’t play nearly as often as I DM.  Many players I’ve known only throw one Fireball inside a dungeon their entire gaming career; even if they survive the first try the resulting blowback is so harrowing they learn to only use the spell in an open environment.
Cole Long asked if I have a rule of thumb for adjudicating Fireball situations and I do.  First I’m going to lay down my basic precepts, them I’m going to run through an example.

1) Make sure the spellcaster has all the info they should have and not a jot more.

This is a general good rule of DMing, but it really matters here.  Distance to target is a key factor for deciding whether to throw a fireball or not, so I’m usually generous in giving out that info.  Put on the spot in a dangerous situation I probably couldn’t decide if a slobbering blugblatter was sixty feet away or seventy, but I lean towards more info rather than less on this point.  I’m going to be hard on the PCs in other ways later, so who cares?  If the party has a map, I usually let the player of the MU mark a small X on the map to indicate the exact placement of the Fireball, unless they say something rash like “I put the Fireball right up the vampire’s nose!”  In which case, I pick the detonation spot.  Usually, I go for the middle of the room.

As with any dungeon operation, lighting is a key factor in limiting player knowledge.  Is the lighting sufficient that they can determine the size of the room they are Fireballing?  If not, they are going to have to find out the hard way.

2) Assume 5’ and 10’ wide dungeon corridors are 10’ tall unless otherwise noted in the key.

The easy way to do this is to count in ‘cubes’, with each stock 10’ corridor equalling one cube, and a normal ceiling 5’ wide corridor as one half a cube.  A 5’ wide corridor with a low ceiling is only a quarter cube per 10’ of distance covered.

IMPORTANT: Do you have giants or other large upright creatures stomping around this dungeon?  To be fair, you might need to assume 1.5 cubes or even 2 cubes ber 10’ of corridor.

3) Assume any room larger than 600’ square feat (i.e. 20’ x 30’) has a high ceiling unless otherwise noted in the dungeon key.

Imagine a 30’ x 30’ room gridded out to 10’ per square.  That center square that does not touch the outer wall of the room?  That’s where the high ceiling is, as far as my rule of thumb goes.  Imagine an extra 10’ x 10’ x 10’ cube over that center square.  So that room is 10 total cubes, rather than the 9 shown on the map.  Similarly, a 30’ by 40’ counts as 12 cubes total, 3x4 plus 2 extra for the 2 center squares.    Here’s a diagram that might help you dig what I am saying:


The 60’ x 60’ room shown is big enough to safely drop a Fireball, as it has well more than the 33½ cubes.  Basically, we are assuming every large room is built like a step pyramid made of empty cubes. 

That’s a gross approximation, but a useful one, much like the spherical cows of physics jokes.  For weird shaped rooms, just try to imagine a similarly-sized rectangular room and make your best guess.  This isn’t rocket science.

SIDE NOTE: In a large enough space a Fireball aimed at the floor/ground will explode into a hemisphere of 25’ diameter.  That’s the way to do it when throwing fireballs at armies.

4) Assume that the concussive blast of the fire can open doors and destroy thin walls. 

I don’t think I have a rule to back me up on this one.  I just like to think of Fireballs as bad action movie explosions.  So when a Fireball effect reaches a door, I roll a normal Open Doors check, i.e. 2 in 6 chance the force of the explosion will throw open the door.  If I roll a 1 then I normally declare the door burst off the hinges.  Because that’s cool.  Also, if the dungeon has any thin walls (‘thin’ defined as the width of a pencil line on the map) I give a 1 in 20 chance of the wall being blown away.  You can deduct one cube of volume for each door opened or wall destroyed, if you're feeling nice.

5) Assume the fire flows like a swift liquid, running in all possible directions equally.

Every time the widening effect of a Fireball reaches an intersection, it will choose both/all directions. That includes pits, chimneys, shafts, stairs.  A well-place vertical tunnel can really save the PC’s bacon.

6) Don’t forget to melt the loot!

Know what rules about breaking stuff you prefer and enforce the heck out of them.  BX D&D notes that fire damage reduces all jewelry to half value (pB47).  OD&D indicates fire will melt jewelry sufficiently to reduce value by 25% and gives an optional 10% chance of heat destroying gems (Monsters & Treasures, last page).  AD&D1 has the awesome Item Saving Throw charts (DMG p80):

item type---save vs. fireball
gem/small stone---7+
jewelry/metal, soft---18+
metal, hard---6+
paper/parchment---25+  [yes, on a straight d20 roll]
rope/wood (thin)---15+
rope/wood (thick)---11+

And remember to melt a bunch of the gold and copper coins!  I’ve had players use crowbars to pry up lumps of melted metal where the dragon’s hoard used to be.  I’ve also done straight up 50/50 rolls for anything I think might burn.  A fun trick is to hand the players a list of loot and then make the poor bastards roll the dice themselves and cross off the stuff they almost had.

7) When in doubt, set the party on fire.

If you aren’t sure about ceiling heights in some areas or you use a lot of weird-shaped rooms with hard-to-estimate volumes, just light ‘em up.  Every self-respecting adventurer gets set on fire by a comrade at some point.  It’s a rite of passage.


The party consists of three PCs, a fifth level fighter named Sturm Von Drang, a fourth level magic-user Merlac the Malevolent, and a third level elf, Organa le Fay, Faerie Princess of Alderaan.  The party is accompanied by two of Sturm’s henchweenies, Bob (F2) and Notbob (F1).  They are looting the Pits of Paratime, having entered the current level from the staircase located at room 52 (bottom left corner).

Sturm has opened the northern door of room 45 (at the apex of the triangle) and the group is proceeding along the long north-south corridor at mapping speed, Sturm and Princess Organa in the lead, followed by Merlac and Bob, with Notbob bringing up the rear.  Both the Princess and Notbob are carrying hooded lanterns equipped with Continual Light sources.


As the party starts to creep past the doors to rooms 42 and 44 (which they opt not to open), the light from Organa’s magicked lantern starts to pour into room 29.  Seven figures come into view.  The Dm describes six of them as primitive reptilian humanoids.  He’s vague (as usual) but they’re probably lizard men, possibly troglodytes, maybe sleestacks.  The seventh he describes thusly: “The last reptile man stands taller than the rest by a full head, which I will get back to in a moment.  His body is proportioned like a Greek God, albeit green and slightly scaly.  Instead of the brutish clubs the others wield, this one holds a shiny silvery trident that refracts your Continual Light into a rainbow of bad lens flare effects.  Oh, and he has a bunch of tentacular eye-stalks sprouting from his head in random locations.”

“By Crom’s Stanky Loincloth, a DM custom monster!” shouts the fighter.

“I’ve got a bad feeling about this,” deadpans the elf.

“Fuck that with a stick!” cries the magic-user, as he pulls a stick out of his sleeve.  It’s the wand of fireballs he stolefound last session.  Dude’s been dying to use it on someone and a half lizard king/half beholder sounds like just the right guy.  “I fireball his stupid face.”

Sturm and Organa see what’s about to go down and do a simultaneously slow-mo “Nooooooooooo!” as Merlac intones the command words “Goodness gracious!”  A pea-sized pellet of shimmering green energy flies through the air, stopping in front of the DM’s pet horror just long enough for three or four eyes to blink, then hellfire explodes all around it.

This old fashion wand does a flat 6d6 damage and Merlac rolls an astonishingly good 32 points of damage.  The DM forgets that lizard men have 2+1 hit dice rather than 2, so he declares all the normal foes in the room dead (including the four the party hadn’t seen yet).  He saves figuring out whether the Big Bad is dead for last, because the DM’s a dick.  Instead, he turns to the volume of the expanding fireball.

Room 29 is 40’ by 30’, that’s 12 cubes plus 2 for the step pyramid approximation outlined above.  The DM checks the key and see that it notes the room as possessing a “high vaulted ceiling”, so he graciously adds one more cube to the total.  Out of 33.5 cubes, we’ve accounted for 15 of them.

There are five ways the flame can pour out of the room, all of which the fire will attempt to use.  First, the fire will take up a half a cube flowing to each door.  At the same time, I’d mark one cube down each corridor.  Like this:

That’s four more cubes of fire, 19 total thus far.

Now it’s time to roll dice.  Is either door forced open by the blast?    So 2 rolls of d6, each 1 rolled indicating the door is blasted off its hinges, each roll of 2 meaning it is merely forced open.  I roll a 1 for the door to room 30 and a 5 for the north door.  The former is blown away, the latter holds fast.

What about the secret door?  For the latter, I’d check to see if my key had any specifics about the door.  Is it particularly massive or flimsy?  Let’s assume no and treat the secret door the same way we would a regular door.  A roll of 1 also blows it open.

Looking at the map, nothing weird is going to happen until the fire reaches room 33, so we can advance the fire like so:


That’s 14.5 cubes beyond the initial 15 of the room, for 29.5 cubes total.  We’ve got only four cubes left and five directions it can flow, so it looks like the party is safe… this time.  The remainder of the fireball fills room 30, setting any inhabitants on fire.  Anyone in room 31 probably sees the flames light up their section of the dungeon.  The door to room 33 holds, but the inhabitants of it certainly hear the blast.  I’d roll a hear noise check for anyone in areas 28, 42 and 44 as well.  There are a lot of doors to control the flow of sound on this level.  In a more open, flowing arrangement I would also throw an extra wandering monster check.

The party lucks out, the fireball ends about 10’ from the front rank.  Had one more door not blown open, the PCs would be on fire right now.  Sturm and Organa give Merlac six shades of hell for throwing grenades when nobody has cover.  Meanwhile the Lizarolder slinks away to find reinforcements.  Bob might have noticed this, but a quick 50/50 roll indicates that he was momentarily distracted by the sight of the wall of flaming death rushing down the corridor and opted to soil his armor rather than watch for escaping monsters.

Final note: I normally shade in the fireball area as scorched on my map if there’s any chance another expedition will visit the dungeon.

Close Effin' Call