Rubiks
Rubiks is a daemon which, when triggered, raises firewalls on all unhacked mainframe devices by 1. Rubiks also affects devices which are rebooting, and inactive Security Cameras.
Strategy
Rubiks can be one of the more dangerous daemons if it is triggered early in a mission, when there are still many devices left to hack, especially if you are short on PWR and especially if you do not have an efficient breaker program. On the other hand, if triggered late in a mission after you have already hacked the devices you want to hack, then Rubiks' effect is relatively weak. So to mitigate Rubiks, you should usually hack other devices before triggering it.
When playing with Golem or Mercenary, or another breaker which hacks 2 firewalls per use, then it depends on the parity of the firewalls. When most firewalls are odd numbers, Rubiks is mostly harmless; but if most firewalls are even numbers, then after Rubiks is triggered you will need to use your breaker more times, typically costing a lot more PWR.
If you have a Wrench installed, Rubiks can be beneficial in some circumstances, because it may raise firewalls to the exact level required by Wrench, allowing devices to be hacked efficiently.