Techmarine

Independent characters can join other units.  They cannot, however, join units that contain vehicles or Monstrous Creatures.  They can join other Independent Characters, though, to form a powerful multi-character unit!  Independent Characters pass Look Out, Sir rolls on a 2+. A unit that contains one or more Independent Characters does not need a double 1 to Regroup if reduced to below 25% of its starting numbres, but instead tests as if it had at least 25% remaining.

Full details in BRB. Rule too long to copy verbatim.

A unit that contains at least one model with this special rule automatically passes Fear and Regroup tests. When it Regroups, the unit does not make the 3" Regroup move, but can instead move, shoot (or Run) and declare charges normally in that turn. Furthermore, if a unit containing one or more models with this special rule is caught by a Sweeping Advance, they are not destroyed, but remain locked in combat instead.

When choosing an army, all models in the same Detachment or Formation must be drawn from the same Chapter.  If a unit's datasheet contains a Chapter in brackets after the Chapter Tactics special rule - for example, "Chapter Tactics (Ultramarines)" - the unit must always be drawn from this Chapter, and therefore cannot be included in a Detachment or Formation with any units that are drawn from other Chapters. All models drawn from a given Chapter benefit from that Chapter's Special Rule. If a unit contains models drawn from two different Chapters, it counts as from neither Chapter, and thus benefits from neither Chapter Tactic.

In each of your Shooting phases, instead of firing his weapons, a Techmarine can choose to repair a single friendly vehicle that he is in base contact with or embarked upon. To repair a vehicle, roll a D6 and add 1 for each servitor with a servo-arm in his unit and an additional 1 if the Techmarine has a servo-harness.  If the result is a 5 or more, you may either restore a Hull Point lost earlier in the battle, or repair a Weapon Destroyed or Immobilised result suffered earlier in the battle; this is effective immediately.

After deployment, but before Scout redeployments and Infiltrate deployments, nominate one piece of terrain in your deployment zone (this cannot be one you have purchased as part of your army).  The terrain piece's cover save is increased by 1 for the duration of the game (to a maximum of 3+). Note that a piece of terrain can only be bolstered once.