DFHACK_DUST seems to default to the very first inorganic entry it can find, in my case "small fire gems".
DFHACK_WEB also default to the very first inorganic entry it can find.
Lavamist is extremely potent and kills almost instantly.
Dragonfire is the same, insant kills.
I couldnt find a difference between mist and mist2.
Mist, Mist2, Miasma, Dust and smoke have no ill effect on the target.
Undirected gas and vapor default to "boiling magma", causing no ill effect.
Ocean waves and sea foam have no ill effect on target. They also wont spawn water, wont put out fire or wont clean the tiles.
DFHACK_DISAPPEAR only removes intact ammo that landed somewhere. Broken ammo tiles will remain.
All tests done with metal bolts of these materials in the arena. No catapult or thrown weapon tests.
[INORGANIC:ZZZ_MAGIC_AMMO_MIASMA]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL:miasma][REACTION_CLASS:DFHACK_MIASMA] [REACTION_CLASS:DFHACK_FLOW_SIZE]
[REACTION_CLASS:20]
[ITEMS_AMMO][MATERIAL_VALUE:5]
[INORGANIC:ZZZ_MAGIC_AMMO_MIST]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL:mist][REACTION_CLASS:DFHACK_MIST] [REACTION_CLASS:DFHACK_FLOW_SIZE]
[REACTION_CLASS:20]
[ITEMS_AMMO][MATERIAL_VALUE:5]
[INORGANIC:ZZZ_MAGIC_AMMO_MIST2]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL:mist2][REACTION_CLASS:DFHACK_MIST2] [REACTION_CLASS:DFHACK_FLOW_SIZE]
[REACTION_CLASS:20]
[ITEMS_AMMO][MATERIAL_VALUE:5]
[INORGANIC:ZZZ_MAGIC_AMMO_DUST]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL:dust][REACTION_CLASS:DFHACK_DUST] [REACTION_CLASS:DFHACK_FLOW_SIZE]
[REACTION_CLASS:20]
[ITEMS_AMMO][MATERIAL_VALUE:5]
[INORGANIC:ZZZ_MAGIC_AMMO_LAVAMIST]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL:lavamist][REACTION_CLASS:DFHACK_LAVAMIST] [REACTION_CLASS:DFHACK_FLOW_SIZE]
[REACTION_CLASS:20]
[ITEMS_AMMO][MATERIAL_VALUE:5]
[INORGANIC:ZZZ_MAGIC_AMMO_SMOKE]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL:smoke][REACTION_CLASS:DFHACK_SMOKE] [REACTION_CLASS:DFHACK_FLOW_SIZE]
[REACTION_CLASS:20]
[ITEMS_AMMO][MATERIAL_VALUE:5]
[INORGANIC:ZZZ_MAGIC_AMMO_DRAGONFIRE]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL:dragonfire][REACTION_CLASS:DFHACK_DRAGONFIRE] [REACTION_CLASS:DFHACK_FLOW_SIZE]
[REACTION_CLASS:20]
[ITEMS_AMMO][MATERIAL_VALUE:5]
[INORGANIC:ZZZ_MAGIC_AMMO_FIREBREATH]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL:firebreath][REACTION_CLASS:DFHACK_FIREBREATH] [REACTION_CLASS:DFHACK_FLOW_SIZE]
[REACTION_CLASS:20]
[ITEMS_AMMO][MATERIAL_VALUE:5]
[INORGANIC:ZZZ_MAGIC_AMMO_WEB]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL:web][REACTION_CLASS:DFHACK_WEB] [REACTION_CLASS:DFHACK_FLOW_SIZE]
[REACTION_CLASS:20]
[ITEMS_AMMO][MATERIAL_VALUE:5]
[INORGANIC:ZZZ_MAGIC_AMMO_GAS_UNDIRECTED]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL:undirected gas][REACTION_CLASS:DFHACK_GAS_UNDIRECTED] [REACTION_CLASS:DFHACK_FLOW_SIZE]
[REACTION_CLASS:20]
[ITEMS_AMMO][MATERIAL_VALUE:5]
[INORGANIC:ZZZ_MAGIC_AMMO_VAPOR_UNDIRECTED]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL:undirected vapor][REACTION_CLASS:DFHACK_VAPOR_UNDIRECTED] [REACTION_CLASS:DFHACK_FLOW_SIZE]
[REACTION_CLASS:20]
[ITEMS_AMMO][MATERIAL_VALUE:5]
[INORGANIC:ZZZ_MAGIC_AMMO_OCEAN_WAVE]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL:ocean wave][REACTION_CLASS:DFHACK_OCEAN_WAVE] [REACTION_CLASS:DFHACK_FLOW_SIZE]
[REACTION_CLASS:20]
[ITEMS_AMMO][MATERIAL_VALUE:5]
[INORGANIC:ZZZ_MAGIC_AMMO_SEA_FOAM]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL:sea foam][REACTION_CLASS:DFHACK_SEA_FOAM] [REACTION_CLASS:DFHACK_FLOW_SIZE]
[REACTION_CLASS:20]
[ITEMS_AMMO][MATERIAL_VALUE:5]
[INORGANIC:ZZZ_MAGIC_AMMO_DISAPPEARS]
[USE_MATERIAL_TEMPLATE:METAL_TEMPLATE]
[STATE_NAME_ADJ:ALL:disappears][REACTION_CLASS:DFHACK_DFHACK_DISAPPEARS]
[ITEMS_AMMO][MATERIAL_VALUE:5]
Conclusion:
Flowsize 1 only affects the tile that is hit.
Flowsize 20 gives a max of 4x4 tiles of gas, or 1-3 webs.
Flowsize 50 gives about 12x12 tiles of gas. Similar to the original vanilla dust from cave ins
Flowsize 10000 gives about 32x32 tiles of gas. Denser then before, but you cant get a higher radius then this.
DFHACK_MIASMA: Useless, might give negative thoughts to civ.members, nice graphical effect.
DFHACK_MIST: Useless, might give positive thoughts to civ.members.
DFHACK_MIST2: Useless, might give positive thoughts to civ.members.
DFHACK_DUST: No damage, Bug: Uses first inorganic entry in the raws.
DFHACK_LAVAMIST: Instakill, starts fires as well.
DFHACK_SMOKE: No damage, nice graphical effect.
DFHACK_DRAGONFIRE: Instakill, starts fires as well.
DFHACK_FIREBREATH: Small fire damage, starts fires as well.
DFHACK_WEB: Awesome to web from a distance. Bug: Uses first inorganic entry in the raws.
DFHACK_GAS_UNDIRECTED: No damage, but can carry syndromes.
DFHACK_VAPOR_UNDIRECTED: No damage, but can carry syndromes.
DFHACK_OCEAN_WAVE: Nice graphical effect, otherwise useless.
DFHACK_SEA_FOAM: Useless
DFHACK_DISAPPEARS: Awesome to avoid clutter, destroy all those single bolts/arrows lying around.
Personally I can see my evil mages use miasma-weapons to lower the happyness of hit units, have some magical elven nonsense with water-ocean-wave arrows just for the looks, make smoke grenades with an unconciousness syndrome, use disappear to reduce clutter, use firebreath for grenades, use dragonfire for very powerful grenades, use web in magical ammo slowing the invaders down.
Question: Any ideas how to use the mist generation on friendly dwarves? If you can create mist from this, cant you write a plugin that creates mist from a workshop? Would be really nice for a sauna or something, to raise happiness. Same for miasma of course, I could add it to the tanner/slaughterhouse for example. Lower happiness for dwarves working in these not-so-pleasant jobs.
Suggestion: You should probably say somewhere that people have to write "projectileExpansion" into their dfhack init, otherwise it wont do anything.
EDIT: Here the raws for people that want to test siege engines with this:
[REACTION:CHEAT]
[NAME:catapult and ballista test]
[BUILDING:STILL:NONE]
[PRODUCT:100:6:BALLISTAPARTS:NONE:METAL:STEEL]
[PRODUCT:100:6:CATAPULTPARTS:NONE:METAL:STEEL]
[PRODUCT:100:1:BOULDER:NONE:INORGANIC:ZZZ_MAGIC_AMMO_MIASMA]
[PRODUCT:100:1:BOULDER:NONE:INORGANIC:ZZZ_MAGIC_AMMO_MIST]
[PRODUCT:100:1:BOULDER:NONE:INORGANIC:ZZZ_MAGIC_AMMO_MIST2]
[PRODUCT:100:1:BOULDER:NONE:INORGANIC:ZZZ_MAGIC_AMMO_DUST]
[PRODUCT:100:1:BOULDER:NONE:INORGANIC:ZZZ_MAGIC_AMMO_LAVAMIST]
[PRODUCT:100:1:BOULDER:NONE:INORGANIC:ZZZ_MAGIC_AMMO_SMOKE]
[PRODUCT:100:1:BOULDER:NONE:INORGANIC:ZZZ_MAGIC_AMMO_DRAGONFIRE]
[PRODUCT:100:1:BOULDER:NONE:INORGANIC:ZZZ_MAGIC_AMMO_FIREBREATH]
[PRODUCT:100:1:BOULDER:NONE:INORGANIC:ZZZ_MAGIC_AMMO_WEB]
[PRODUCT:100:1:BOULDER:NONE:INORGANIC:ZZZ_MAGIC_AMMO_GAS_UNDIRECTED]
[PRODUCT:100:1:BOULDER:NONE:INORGANIC:ZZZ_MAGIC_AMMO_VAPOR_UNDIRECTED]
[PRODUCT:100:1:BOULDER:NONE:INORGANIC:ZZZ_MAGIC_AMMO_OCEAN_WAVE]
[PRODUCT:100:1:BOULDER:NONE:INORGANIC:ZZZ_MAGIC_AMMO_SEA_FOAM]
[PRODUCT:100:1:BOULDER:NONE:INORGANIC:ZZZ_MAGIC_AMMO_DISAPPEARS]
[PRODUCT:100:1:SIEGEAMMO:ITEM_SIEGEAMMO_BALLISTA:INORGANIC:ZZZ_MAGIC_AMMO_MIASMA]
[PRODUCT:100:1:SIEGEAMMO:ITEM_SIEGEAMMO_BALLISTA:INORGANIC:ZZZ_MAGIC_AMMO_MIST]
[PRODUCT:100:1:SIEGEAMMO:ITEM_SIEGEAMMO_BALLISTA:INORGANIC:ZZZ_MAGIC_AMMO_MIST2]
[PRODUCT:100:1:SIEGEAMMO:ITEM_SIEGEAMMO_BALLISTA:INORGANIC:ZZZ_MAGIC_AMMO_DUST]
[PRODUCT:100:1:SIEGEAMMO:ITEM_SIEGEAMMO_BALLISTA:INORGANIC:ZZZ_MAGIC_AMMO_LAVAMIST]
[PRODUCT:100:1:SIEGEAMMO:ITEM_SIEGEAMMO_BALLISTA:INORGANIC:ZZZ_MAGIC_AMMO_SMOKE]
[PRODUCT:100:1:SIEGEAMMO:ITEM_SIEGEAMMO_BALLISTA:INORGANIC:ZZZ_MAGIC_AMMO_DRAGONFIRE]
[PRODUCT:100:1:SIEGEAMMO:ITEM_SIEGEAMMO_BALLISTA:INORGANIC:ZZZ_MAGIC_AMMO_FIREBREATH]
[PRODUCT:100:1:SIEGEAMMO:ITEM_SIEGEAMMO_BALLISTA:INORGANIC:ZZZ_MAGIC_AMMO_WEB]
[PRODUCT:100:1:SIEGEAMMO:ITEM_SIEGEAMMO_BALLISTA:INORGANIC:ZZZ_MAGIC_AMMO_GAS_UNDIRECTED]
[PRODUCT:100:1:SIEGEAMMO:ITEM_SIEGEAMMO_BALLISTA:INORGANIC:ZZZ_MAGIC_AMMO_VAPOR_UNDIRECTED]
[PRODUCT:100:1:SIEGEAMMO:ITEM_SIEGEAMMO_BALLISTA:INORGANIC:ZZZ_MAGIC_AMMO_OCEAN_WAVE]
[PRODUCT:100:1:SIEGEAMMO:ITEM_SIEGEAMMO_BALLISTA:INORGANIC:ZZZ_MAGIC_AMMO_SEA_FOAM]
[PRODUCT:100:1:SIEGEAMMO:ITEM_SIEGEAMMO_BALLISTA:INORGANIC:ZZZ_MAGIC_AMMO_DISAPPEARS]