Howling Griffons: Chaplain Dreadnought Titus
Titus has the standard profile and rules for a Venerable Dreadnought, with a few extra rules to convey his role as a Chaplain Dreadnought of the Howling Griffons. He has a dreadnought close-combat weapon with heavy flamer or storm bolter, as well as a lascannon (which for some reason isn’t twin-linked like it is for every other Dreadnought) or assault cannon. He also comes with extra armor.
To mimic the Chaplain rules, Titus has Hatred and makes ever friendly Space Marine unit within 12” Fearless. Finally, and perhaps most useful, Titus is scoring if he is your warlord. Very unusually, Titus does benefit from Ultramarines Chapter Tactics even though he’s a vehicle. That’s not a huge change, but it could prove extremely useful throughout the course of the game, particularly benefiting him if he needs to get into assault with a juicy target.
Titus isn’t the most competitive choice, but he is unique as a scoring Dreadnought HQ. He’ll be most useful anchoring a firebase, as he’ll provide some firepower, make the surrounding units Fearless, and act as a counter-charge unit.
Marines Errant: Lieutenant Commander Anton Narvaez
Anton Narvaez is a Captain of the Marines Errant, with the standard statline. He comes with a power sword and master-crafted plasma cannon. To add a bit of durability, he has a special iron halo that provides a 3++ save, but can short out if the save is failed.
The main reason to take Narvaez is his Dark Void Elite, which allows D3 Sternguard, Tactical, or Devastator squads, or Narvaez and his Command Squad, to deploy using Deep Strike. They even roll an extra die for scatter and use the two lowest, making them a bit more reliable. He always has the Rites of War Warlord Trait, so he can pass his LD on to nearby units. He also has extra abilities in Zone Mortalis/Blood in the Void games.
Narvaez is cheap and reasonably well armed, but his main addition is allowing units to deep strike without buying Drop Pods. While a bit less reliable than pods, his ability to teleport in units will save you some points if that’s the style army you want.
Fire Angels: Captain Tarnus Vale
Tarnus Vale has a Captain’s statline and equipment and not much else. He actually has a master-crafted chainsword. He doesn’t do much on his own, but he adds a lot to a mechanized army. Any tank that he rides in gets his BS 5 and Tank Hunters. In addition, all Rhinos, Razorbacks, and Land Raiders in his detachment get a 5+ invulnerable save against glancing. He also comes with the excellent Storm of Fire Warlord trait as well, and is reasonably priced for his abilities.
Vale is definitely at his best when riding in a Land Raider. BS5, twin-linked Tank Hunting lascannons that can engage 2 different targets are really good. Beyond that, the invulnerable save he gives to transports is most useful for Land Raiders, which tend to die from lots of glancing hits because they are so difficult to penetrate. If you want to run multiple Raiders to overwhelm you opponent’s anti-armor abilities, Vale is the HQ for you. If you won’t be running Raiders, skip him, as he doesn’t add much to other vehicles in the army.
Novamarines: Captain Mordaci Blaylock
Mordaci Blaylock is a Captain in Terminator armor. He carries a storm bolter and a master-crafted, Shredding chainfist. That’s all well and good, but he’s nothing special on his own. His main draw is that he makes all of your Terminator and Terminator Assault squads scoring. If you want to run Terminator heavy Ultramarines, Blaylock makes the list much better by making all of those squads scoring. Beyond that, Blaylock will allow any squad he joins to choose to pass and fail any morale test, and are also immune to pinning. That gives you at least one completely reliable, very durable scoring unit. He also comes with the useful (if situational) Champions of Humanity Warlord trait.
Mordaci is the choice for running a Terminator heavy army out of Codex: Space Marines, but won’t bring much to other army types.