I've not seen anyone mention these, and I am confused because they are just silly.
A Powder Keg is a 5lbs keg of blackpowder. Normally it costs 1000gp to make, however with the gunsmithing feat it only costs 100gp and requires 0 points in any crafting skill. Powder Kegs are vulnerable to fire and electricity, and when exposed they explode and deal 5d6 damage in a 20ft radius with a DC15 reflex save for half. While this isn't anything spectacular, it sure does a lot more damage to a lot more people than throwing an alchemist's fire.
Unless you have the Throw Anything feat (or are a Barbarian Hurler or have some method of increasing range increments or reducing the range increment penalty) you are looking at an attack roll of 13 to land the keg 25ft away from you. The trick is to set these off on the same round that you throw them.
That is actually difficult, since the easiest way to draw a powderkeg is as a move action from a Handy Haversack. Unfortunately, that limits you to a single standard action where you need a standard to throw the keg and another action to ignite it.
Does anyone have any ideas as to how you can get this whole nonsense off in one turn? The lower the level you can manage it, the better, since even an infinite number of 5d6 powder kegs doesn't matter too much at higher levels.
Spark is a spell thats great for this combo (with GM acceptance). Just need to attack a fuse of the required size, and get a familiar with a wand. Range @ CL 1 is exactly 25', and a wand monkey familiar is hardly without other uses. Minimum investment of 2 feat and waiting till level 7 to do this in one turn. Maximum investment of 4 feats and 9th level. And I suppose 375+100/keg gold pieces for wand and ammo.
Alternatively, you could work in tandem with your party blaster to set off the keg at the limit of a fireball's radius. Or at the center to add a bit of damage. Its even better with a team alchemist who is already willing to do a bit of fire AoE damage, especially with the reduced radius of bombs. Of course, cohesive parties aren't always present, and some people won't be fond of building around this gimick so maybe don't rely on this.
Of course, this trick is still not going to scale well, but it is a decent way for martials to deal with swarms and helps v. SR at least a little. Avg damage is 18 for the blast, which means fire resistance 10 (common) and a decent reflex save renders a creature nearly immune to it, but its better than the alchemist fire, which is ignored by resistance 5 more often than not.
Teamwork is certainly the best way to pull it off, however I was looking for a way to one-man powder kegs.
I am pretty sure most GMs would nix the idea of a Monk of the Empty hand who draws and throws Powder Kegs like throwing weapons. Still if you could flurry of blows with Powder Kegs that would be absurd. You could even self-detonate them at level 11 with a single ki point. While a single powder keg is silly, throwing 4 of them around a target and detonating them all with a flaming chair-leg is hysterical.
Still, I am pretty sure any sane GM would nix that plan hard.
Still the best method I have found is to have a School Familiar (evocation) since they are capable of casting Spark at will.
If you can throw the keg one-handed you just need a weapon which does fire or electricity damage in the other, and TWF. A +1 shocking pistol perhaps since a gunslinger is the natural way to get gunsmithing.
Edit: Wait, no. Just throw alchemical fire to set it off.
True, though it requires a turn of set-up since you cannot draw the Keg and make a full round attack on the same turn. That is fine if you are using the kegs as swarm killers, but less fine if you want them to be a standard part of your arsenal.
Other than the Death's Head Coffer, I don't think there's a useful way of placing an item (like a lit powder keg) in stasis in pathfinder, and that is both too small and one-use.
EDIT: not sure about the size issue. the coffer can hold a 4x4x6 inch item. [does a bunch of math] Well, that's only about 3.3 lbs. of powder.
Other possibilities:
The Underground Chemist rogue archetype is "able to retrieve an alchemical item as if drawing a weapon" at second level. If your DM agrees that an item made with craft (alchemy) qualifies, then quickdraw solves your problem.
Another option would be a tiefling with the Grasping Tail feat or Prehensile Tail alternate racial trait to "retrieve small, stowed objects carried on your person as a swift action."
Finally, Adroit Retrieval, a third level arcanist/sorcerer/wizard spell allows and touched creature to "withdraw small items from her pockets or packs with supernatural swiftness. When the target retrieves an item stored on itself, it can retrieve the item either as a move action without provoking attacks of opportunity, or as a swift action that provokes attacks of opportunity. This effect functions only when the target attempts to retrieve a stored item that weighs less than 1 pound per caster level (maximum 15 pounds)."
Shrink item does put campfires into stasis at least. Maybe we are looking at a spellslinger wizard here.
Just cast resist energy first. Even resist 20 will negate almost all the damage. Then run in and set it off.
I had a fire domain cleric who did this with fire seeds as well. With resist 30 none of the seeds did enough individually to overcome the resistance, likewise the gunpowder damage to me was negated as well. Just run in, and blow it up. You could even carry a couple. Just make sure to drop them before detonating the seeds. Carried items gain your resistance.
Adroit Retrieval works as soon as get the spell since powder kegs are five pounds, and it lasts for multiple minutes so it allows you to use multiple barrels in a period of time.
Shrink Item would work on a single barrel. However you could have that barrel prepared to explode, though preparing the explosion would be the difficult part as you might just explode while preparing the bomb.
Regardless, both are 3rd level spells which means 5th level at the earliest. On its own though, you are probably better off getting experimental with Explosive Runes. Still, if you had prep-time you could shrink a bunch of barrels, throw them all tied to each other, and then say the command word to make them expand to full size while your Familiar hits the barrels with a spell (or you TWF with a gun).
Would grasping tail work for a 5lbs barrel? And would you carry one on your person exposed? That would be risky, and it also might detonate your other barrels resulting in you ceasing to exist in a rather satisfying boom.
Two levels of underground chemist should work, though you would receive table variation. The creation of black powder was one of the few successful feats of early chemistry or as it was known then, alchemy. Still, GMs might argue that a barrel of black powder isn't an alchemical item. It also runs into the whole "might explode" thing that Grasping Tail provides.
I completely forgot about Energy Resistance, that makes the whole not exploding thing a lot easier.
Instead of throwing them, you should really be rolling them. On terraced, inclined levels. And be a giant gorilla. <g>
More seriously, taking out a barrel of black powder really *should* take more of an action than taking out a vial of acid or whatever. The size and encumbrance are simply not comparable.
Bear in mind that this isn't going to be affordable at 1st-2nd level, it's iffy at 3rd, and if spells take over at 5th that's a very narrow window to build for.
We used this cheese in one of my games, a sorcerer would use wall of fire, and our gunslinger would hurl barrels at the fire, automatically setting them off. Before that, they use readied actions, gunslinger throws barrel, Sorcerer casts spark on the fuse (tiny object alchemically crafted), setting off the barrel with iron spikes (added slashing damage).
I don't recall where we saw these rules, I believe in the future tech splat books (with the machine guns rules)
Or add a tindertwig fuse for your spark target (as spark cannot hurt the barrel itself).
Lastly TWF the barrel and an already lit torch on the same turn, throw anything would be a big help here even to hit the square.
You do want them in a bag, because total cover negate splash damage at least once, meaning you can weather a too close throw.
You could also theoretically use a fire enchanted bow/crossbow to do fire damage vs object (0 damage from pierce, 1d6 fire).
the real question is... if a barrel is dropped (not thrown) by an invisible character... does the invisibility break? We never managed to get an answer on that on these forums, but it is handy to have barrels suddenly appear amongst mooks that your team can target without wrecking invis.
Can you tape or glue or tie an alchemist fire to the barrel ahead of time? Throw both at once, the flask breaks and ignites the cask.
Chuck em with telekinesis