Like the other Scout units in the new Codex: Space Marines book, Scout Bikers got a boost to BS4/WS4, with no additional points cost (and basically no change to their profile, wargear, and rules).
What Scout Bikers did gain, though, was the ability to be chosen as part of a new formation, the 10th Company Task Force. You can choose up to 3-5 units of Scout Bikers (plus Telion, if you want him; Scout Bikers must upgrade with Cluster Mines though) if you take this formation and gain access to two rules:
1 – Concealed Positions — Free Stealth until the unit moves, turbo-boosts, charges, or falls back, then loses it entirely.
2 – The Trap is Sprung — All Scout Bikers gain Precision Shots for the first game turn.
So, how does all this work on the tabletop to best effect? Well, if you take Raven Guard Chapter Tactics, that means that turn 1 all non-vehicle models/models not embarked get Shrouded. Combine that with the “Concealed Positions” rule and the Scout Biker’s ability to Infilitrate/Scout into terrain within 18″ of your opponent’s army and the Scout Bikers have a 2+ cover save that first turn.
Additionally, they have the ability to use their TLed Bolters (and Astartes Grenade Launchers) with BS4 and the Precision Shots rule (from “The Trap is Sprung”) to target key enemy units/characters on the frontline. Additionally, they can use their Locator Beacons to precisely bring in allied units… such as GK Terminators, Strike Squads, Interceptor Squads, and Dreadknights from an allied Nemesis Strike Force.
Imagine bringing in 2 GK Terminator squads and 2 Dreadknights turn 1 right in front of the Scout Bikers… you can basically apply blitzkrieg principles (i.e. overwhelming force at the critical point) with this tactic and outmass your opponent at exactly the place you want to.
So, what does 3-5 squads of Scout Bikers do once they bring in their Ordos Malleus allies?
Well, if you look at it, for only four points more than a normal Tactical Marine, Scout Bikers have the following advantages over an equivelant Tactical Marine:
1 – Mobility — With Scout, Infilitrate, 12″ move, and 12″ turbo-boost, Scout Bikers are EXCEPTIONALLY more mobile than Tactical Marines. This is especially important for seizing objectives, setting up rapid fire shooting, charging enemy vehicles with Krak grenades/MBs, and using their Locator Beacons to bring in reinforcements precisely throughout the game.
2 – Firepower — With BS4 and TLed, Relentless Bolters, Scout Bikers are accross the board more accurate than Tactical Marines. Additionally, they can take up to the three Astartes Grenade Launchers, no matter the squad size, giving them very decent anti-horde and anti-light vehicle options. The only advantage Tactical Marines have here is their ability to take a Special/Heavy weapon or, if they have 10 members, one of each. Scout Bikers cannot take Grav weapons, but other than that their 3 Astartes GLs should be quite versatile and mesh well with the TLed Bolters of the rest of the squad.
3 – Durability — While Tactical Marines have a better armor save, Scout Bikers have better Toughness. When you do the math, against anything from Bolter Fire to Plasma shooting to krak Missiles, Scout Bikers and Tactical Marines end up basically having identical survivability odds. Better yet, Scout Bikers can choose to Jink, giving them a 4++ cover save if they need it, which is generally superior to Tactical Marines’ option to go to ground, especially since Scout Bikers can still move and charge (and even shoot Snapshots) if they Jink.
4 – Combat — While neither Scout Bikers or Tactical Marines are great in assault, Scout Bikers have the advantage on a couple of fronts. First, being much more mobile, they have a significantly improved chance of getting the charge (instead of being the charged themselves). Second, they have Hammer of Wrath attacks, which Tactical Marines do not, and with Raven Guard tactics, they also get to re-roll failed to Wound rolls for those Hammer of Wrath attacks. Finally, because they are Relentless, Scout Bikers can double-tap their target and still charge that same tunr…. all told, a Scout Biker can potentially inflict 5 x S4 attacks on the turn they charge… two Rapid Fire Bolter shots, one S4 HoW attack, and two S4 normal attacks.
5 – Force-multiplying — As already referenced, Scout Bikers have access to Locator Beacons, which is quantitatively superior to Teleport Homers since they work on ALL forms of Deep Strike (not just teleporting Terminators) and even on Gates of Infinity “jumps.” Additionally, while not a major item, their mandatory Cluster Mines allows each squad to make a peice of terrain into Dangerous Terrain to enemy units, which can give a slight edge to your army.
So, why take all this effort to outline how Scout Bikers are superior to Tactical Marines? Well, when used as allies to Grey Knights, Scout Bikers from the 10th Company Task Force can support the initial GK entry into the game, but then for the rest of the battle can serve as a very mobile, durable, and versatile “counterpart” to the much more elite (and expensive, points-wise) Grey Knight units. Overall, I think Raven Guard Scout Bikers and Grey Knights from a Nemesis Strike Force make for a balanced task force in a competitive, all comers list.