You should call the Ordnance Lab (Almayer Tab) and ask them what this does. It will normally be labelled: either a huge blast, or an *-shaped fire (typically 10-15 tiles in each direction from center). Both are capable of huge friendly-fire, even gibbing Marines.
Most people aren’t at all aware of what mortar is actually capable of when the right people come together, so I’ll try my best to explain the most common types of mixtures.
OT custom mortar shells come in two primary categories:
Custom Incendiaries!
Star-shells, decal-bombs and 16-tile mini-OBs.
Star-shells are 8-tile flames spread from a 3x3 nucleus. Incredibly powerful at area denial- but usually a lot weaker at actually killing things caught in the center. Because of how flame-code works, however, they have a higher capacity for direct flame damage compared to non-star-shell custom shells. Ethanol star-shells are incredibly easy to make, and can be produced in bulk- while not sacrificing damage. They’re usually cheaper than buying straight incendiary shells. Incredibly useful if you manage to get the space in the field.
Full range not depicted here.
Nor here. Get a sense of the scale.
Next up are Decal bombs, otherwise knowns as airbursters. These are rarer, most OTs don’t know how to do them, but they offer a greater flame coverage than normal incendiaries and most max-capacity shells for a typically smaller radius. The welder-gas will reignite xenos caught in the center, making it particularly hazardous to push through. Consider them a mixture, or balance of the above and below.
Courtesy of Arbs.
Last up for incendiaries are non-star-shells, or medium-capacities. Trading the higher damage of max-capacity incendiaries with better coverage within the circumference of the blast, these shells are adept at covering untold amounts of space, generally in indoor areas- and will punish xenos far more for trying to maneuver through. Particularly amazing at punishing retreats compared to star-shells larger area denial.
If you don’t like the colours these come in, don’t worry. Depending on what types of Ethanol your OT uses, the resultant mixture will vary greatly. Communicate with your OT before you order.
(Hint: Ask for Thirteen Loko.)
Custom Explosives!
The stuff everyone actually wants. These are a lot easier to distinguish than incendiaries, and usually only differ in explosive power when research develops a powerful explosive/oxidizing chemical.
The usual CYCLO/ANFO mix combines into a (near) max-cap mortar shell with this amount of power. There are alternative mixtures that use more Cyclo for something closer to capacity, but this tends to be the cheapest combination.
Now, if research comes up with an EXP3 chemical, the average OT can make a custom mortar shell with about 120u of beaker-space to spare. This can be filled with either ethanol, or shrapnel. I’ll go into shrapnel further at the end of the post, but it’s harder to visually display compared to the explosion radius.
This is 120u of an EXP3-rated chemical.
Every human in the red, as in, taking more than 200 explosive power (especially with no armor to reduce the explosive power) will get gibbed.
If an OT mortar’s dropping near you and you can’t get out of the way in time, go prone. It might just save your life.
Lastly, shrapnel. It comes in three variants-
Incendiary shrapnel; which sets everything hit with fire equivalent to M240 napalm.
Holo-targeting shrapnel; which travels faster than regular shrapnel, and makes every target hit receive 20% more damage for 5-10 seconds.
Neurotoxic shrapnel; …gives xenomorphs hit the research neurotoxic gas effect, which provides them welder-vision and prevents auto-trigger (on-key-press) abilities from being used. This can, for example, prevent a ravager from hitting shield, a defender from lowering crest, or a queen from screeching. Potentially the oddest version of shrapnel, and because it requires 10u of neurotoxin plasma, it is exceedingly rare.
Every version of shrapnel that isn’t unmodified will reduce the amount of shrapnel created by 75%. This means that it’s usually added best on top of shell combinations that either don’t use a lot of reagents and can offset the reduction in target acquisition through sheer bulk of iron, or with specialized combinations of the above types. Get creative.
That should cover everything. Every shell can be customized for a specific purpose, just make sure to talk to your OTs and have an idea of what you want (or want to do). Happy ‘sploding. Blurst every day.