The Fist of Medusa Strike Force is available to armies of the Iron Hands and their successors. In general, it accentuates the already considerable durability of Iron Hands, and I think it will prove to be one of the strongest Space Marine detachments.
It brings 3 Command Benefits. Logical Commander allows your Warlord to take an extra Warlord Trait from the Tactical or Strategic Tables. An extra Warlord trait is always handy, and being able to take it from the very useful Strategic table is amazing. Other armies pay for Relics (such as the Finkin' Cap and Veritas Vitae) to get this benefit and consider themselves lucky. Reject the Flesh, Embrace the Machine grants any model in the Detachment +1 to their Feel No Pain rolls while within 12" of an Independent Character from the Detachment. This grants most Iron Hands a standard 5+ Feel No Pain, while a Command Squad gets a 3+ Feel No Pain and a character with the Gorgon's Chain can have a 2+ Feel No Pain. Space Marines don't get any tougher than that. Roused Machine Spirits grants Power of the Machine Spirit to vehicles in the Detachment within 12" (or while carrying) an Independent Character from the Detachment. This makes the vehicles extremely flexible, able to divide fire or maintain their firepower when shaken or stunned.