Moving on to the 10th legion, the Iron Hands.
These guys are hard to shift. Legion Astartes Iron Hands have a rule called Involite Armour, this reduces the strenght if all shooting against them by 1, making bolters Str 3 against them. This is AWESOME. They have some pretty major draw backs; must pass a leadership check to RUN or SWEEPING ADVANCE, which SUCKS IN 30K, where you need to SWEEPING ADAVANCE. Theses guys want to stay out of charge distances and out shot the opponent.
You will want to leverage Involite Armour with with t5: Out rider Bikes, Attack bikes, Jetbikes. Unfortunately you may not take more bikes jetbikes and jump infantry that infantry squads. This SUCKS. but how ever... Put your Praetor in a bike squad and he will never instantly die to Shooting, and will be a nightmare to wound. Str 3 bolters vs Toughness 5 with 2+ 4++.
These units are the fast options your army otherwise lacks as you are building an infantry centered list. As such this army will often be footslogging if you want to be the most efficient with your legion choice and points spent.
Also your units may never voluntarily go to ground on that ap3 will kill you
Characters can pretty cheaply take cyber familiars for +1 invol to max of 3++ (Or a 6++) and it DOESNT TAKE UP A HAND AWESOME.
Your relic is awesome against tanks, especially Spartans as Flare Sheilds don't work against Grav. Assault 3 is awesome with grav, it is template so you will be up close and personal where the iron hands DONT LIKE TO BE, STAY BACK AND OUT SHOOT THEM (drop site massacre lolz). Don't let the ap3 make you think this is anti marine. This GRAVITATION NOT GRAV so it makes you take a toughness or strength test? So it's wounding marines on a 5.
It's very nice at what it does: kill vehicles.
The Rite of war is very strong, all vehicles get a 6+ IWND for FREE, any model with a Flamer may take a GRAVITATION gun for 10 points (has haywire). Tanks in reserve get outflank (nice I guess)
But the major issue is only one fast attack slot.
Take your praetor on a bike, give him a halo, and the relic (extra flavour to your choice), then take outriders, give them twin link flamers, then upgrade those to twinlink gravitation guns. 12" move T5 -1 shooting against them (can't be instant deathed by shooting strenght) and 3+ save 4+ jink with Haywire guns. CHEESE.
Also only one consul allowed other than Forge Lord consuls so no taking multiple chaplains, also if your taking this with a delegus, no more consuls unless they're Forge Lords.
Special units: Gorgon Terminators; These guys are nasty, 2+ save 5++ invol, -1 Str for shooting against them and a 5+ FNP. Also on a successful save (that includes the 2+ armour) on a D6 of a 4+ all units within 6 must test for blind. FOR EACH SAVE, NOT JUST ONCE. Friendly units can reroll the blind test.
Because it's not Cataphracti armour they can over watch. They can also take gravitation guns as special weapons in addition to the normal special weapons. Everyone has power axes but can take lightning claws so eat blinded enemies (they are I3 normally though). They still have to take a Leadership to run, just shoot with these guys and do point denial. They won't want to charge you, they won't really want to shoot you, (Move these guys ahead of your main army so they don't blind your own units (facepalm)). Also that FNP is here to stay agaist shooting, your opponent will need a las cannon or better to get rid of it because if Involite Armour (the -1 Str for shooting against them).
It is important to remember that that rule only effects legion astartes, therefore not your tanks and other vehicles.