Flare is a breaker program which breaks 4 firewalls, but also raises the firewalls on all unhacked mainframe devices by 1 when it is used. It costs 0 PWR to use, and has a cooldown of 3 turns. Flare can be bought from some Server Terminals for 450 credits.
Flare raises firewalls on devices after breaking them on the target device, so if Flare is used to fully break the firewalls on a device, its firewalls are not also raised by 1; otherwise they are, so Flare effectively breaks 3 firewalls in this case. If Flare is used to hack a device with a daemon installed, then the daemon's effect is triggered before Flare raises firewalls; for example Flare also raises the firewalls on a device recaptured by Echo.