[daku]

reefer ? poisonous gas ?

try partially filling these tunnels with acetelyne, then launch some munition (at a safe distance)

film it please, I'd like to see what happens

[Petruchio]

try partially filling these tunnels with acetelyne

Good idea. When the acetelyne is ignited it will do 2 things:

1- Create a high pressure wave through the tunnels.

2- Consume all the available oxygen.