This week, we move from Greenskins to the iconic favorite of little kids everywhere, Space Marines. Though the space marine codex is a 5th edition codex and even written by the much maligned Matt Ward, it is outclassed by most specific Space Marine codices in its current iteration. Currently, it really only has a few competitive builds, most focusing on a specific character: ie. Kayvaan Shrike, Korsarro Khan, Pedro Cantor or today's subject Vulcan He'stan.
Vulcan is a solid special character in combat, having a number of nice pieces of wargear (Relic Blade, Heavy Flamer, 2+ armor and 3++ invulnerable). However, his special ability is the reason he is so popular and potent. He replaces the standard Combat Tactics ability of a space marine army with the ability to treat all Melta and Flamer weapons (but not Flamestorm Cannons) as Twin-Linked, and to treat all Thunder Hammers as masterwork. Obviously, making some of the best weapons in the game more reliable is a potent army wide ability, and because of it, his armies are always built to exploit this rule. Typically, they come in one of two forms: Drop Pod lists, or Hammer lists.
Drop Pod lists use multiple drop pods to get as many units with melta and flamer weaponry into range as soon as possible (first/second turn, typically). Due to the drop pod assault rule, several pods will arrive first turn, typically full of Dreadnoughts with Multi-Melta/Heavy Flamer and/or Sternguard with multiple combi-melta or combi-flamer. This allows a potent alpha strike. The Hammer lists use squads of Thunderhammer/Storm Shield terminators, typically in land raiders, to rapidly approach and engage the enemy in close combat. Already fearsome units, the added reliability of Mastercrafting makes them devastating, especially with a Librarian with Nullzone nearby. The hammernators are backed up by the same suite of melta/flamer heavy support units (such as attack bikes, landspeeders, dreadnoughts) as the drop variety.
Vulcan - As the namesake of the army, he is in every list. His ability to increase the killing power of the whole army is impressive.
Dreadnoughts - Armed with a Multi-Melta and Heavy Flamer, and usually dropped in a pod, they are very powerful and reasonably priced units which mesh well with Vulcan's special rule.
Hammernators (Assault Terminators with Thunder Hammer/Storm Shield) - The Cornerstone of the Hammer list. Already a very effective close combat squad with lots of survivability, the increase in killing power from Vukan makes them even better.
Sternguard - When equipped with combi-meltas, they benefit a lot from Vulkan's rule. Lots of killing potential in a reasonably priced package. Compete with Dreadnoughts though, so are less common.
Landspeeders - Great source of quick Multi-melta and/or Heavy Flamer.
Librarian - Nullzone is already a great power, and with this list you force your opponent to rely on invulnerably saves a lot. Making them re-roll is invaluable.
Ironclad Dreadnought - Some prefer these heavier armoured dreadnoughts, especially since the INAT faq which allows them to use the Chainfist Upgrade and keep the bonus attack for 2 DCCW. Also have a melta-gun.
Drop List - Drop in as many pods as possible first turn, saving empty pods or pods with tactical squads for later. Always aim for an odd numbers, as that will let you drop the most amount of pods on turn 1 with keeping the fewest in reserve. ie. 5 pods, or 7. Be aggressive and try to weaken/destroy as many targets as you can first turn, especially transports (as after that first turn, you will lose on mobility AND range).
Hammer List - Come in hard and strong. Use smoke to avoid the land raiders being taken out first turn and hope for a second turn assault. Depending on opponent, you may want to use flamers to take out screens and attempt to get into position to assault past those screens. Unlike other assault heavy armies, you are most worried about being outrun, not being caught in the open and shot (as you are very durable) so again, transport busting should be a focus early on (and any Demolisher Cannons or heavy plasma units your opponent has).