Documentation
Emergency lines within the sewer system vent gasses to prevent explosions, but what's the fun of that? Get a couple of those redirected with your gang's help and you can fill the entire tunnel with a spark. It'll be awesome!
Use
Dockside Sewers (available with Annotated Maps)
Start text
In combat:
Without an air filter:
You hear a few pings and pops, then the entire tunnel starts to smell foul… more foul, like eggs that have gone so rotten that their scent cuts through the underlying smell of sewage.
With an air filter:
You hear a few pings and pops, then you pick up on a faint hissing that makes you rather glad you're wearing a gas mask.
Inbox text:
You vented some sewer gases into the tunnel. Time to hide the explosives… or break them out.
Effects
When both players oppose each other with fire techs, said fire techs do much more damage, with the message:
The tunnel is filled completely by fire.
If a fire tech is opposed by evasion, the evasion technique fails to block any damage, and the fire technique gains the message:
Fire fills the tunnel, leaving nowhere to hide.
(but does not increase in damage?)
Unless the player using the evasion technique has a Midgard blastshield equipped:
Fire fills the tunnel, leaving nowhere to hide except behind your blastshield, which prevents all but <x> damage.
(could test with other shields or equipment)