Improved Fougasse is a pre-battle deployment option in Empire: Total War.
Improved Fougasse is deployed identically to Fougasse: in a small box; a red plume indicates the area which the enemy needs to step into in order for it to detonate. The only way improved fougasse differs over fougasse is the resultant damage from activation of the mine: while fougasse merely sends a shower of debris towards enemies, improved fougasse also sends a shower of grenades, which detonate a few seconds after release.
It can usually only be deployed by rifle-equipped troops such as Riflemen and their equivalents. Certain musket-armed light infantry, particularly those available with the DLCs, also have access to Improved Fougasse. Examples include Haydut Irregulars and Company of Select Marksmen/Fraser's Rangers.