Golem
Golem is a breaker program which breaks 2 firewalls for a variable PWR cost, with no cooldown. Golem can be chosen as a starting program, or bought from some Server Terminals for 500 credits.
Golem initially costs 4 PWR to use, and its cost decreases by 1 PWR at the start of each turn (except for the first turn in the mission), down to a minimum of 0 PWR; the cost to use Golem is reset to 4 PWR each time it is used.
Golem is found in the Contingency Plan DLC.
Strategy
Golem is a versatile breaker, which can be used either frequently with a higher PWR cost, or occasionally with a low PWR cost. If Golem is used frequently then its average PWR cost per firewall broken is slightly less than Lockpick's; if used once per turn then it is effectively Lockpick 2.0. If Golem is used once every four turns, then it costs no PWR at all. Golem is therefore similar to Parasite and Mercenary, in that it is more PWR-efficient when you use it for some but not all of your hacking.
When playing with Golem as a starting program, it will generally be less efficient because you often need to hack devices with just 1 firewall, or an odd number of firewalls. Typically, you will want to install a second breaker quickly, before hacking everything with Golem costs too much PWR.
Golem pairs well with Seed, which allows you to use Golem once per turn for free, and later once you can do some hacking with other programs, Golem can be used less often, becoming one of the low-PWR-cost programs you use after your “free” hack per turn.