Legion Herald
The Legion Herald was a type of informal command rank given to Space Marines during the Horus Heresy. They were effectively, for all intents and purposes, the flag and standard bearer of its time period, ancient Primaris Ancient.
Overview
These officers carried the official banner of their lords, be they Primarch or otherwise. They often oversaw and undertook the interests of their Legions in key missions, acting most commonly as emissaries. They have what some in /tg/ may speculate, one of the easiest jobs in the Legiones Astartes during the Great Crusade. Although said job kind of went kaput due to Horus' temple tantrum. Heralds usually wore Artificer Armour due to the symbolic importance of their role.
Crunch
Whilst not much is put into their fluff, a shit ton can be given out in the crunch. Heralds are a 40pt upgrade which grants some pretty sizable buffs to your army depending on which Faction you are (looks like in Book 6 they are really hammering down on picking a Faction rather than having Loyalists and Traitors a campaign thing). Now the limitations: cannot be the compulsory HQ (so no Herald for allies, kinda unfluffy IMO), and can take a Rite of War, your enemy scores an additional VP if the Herald dies, cannot benefit from additional CCW (as he's holding a MF banner), may not take a jump pack/jetbike/bike/terminator armour, may not take any weapon which is Two-Handed. Always best giving the Herald Artificer Armour and possibly a power fist since the Specialist Weapon downside makes zero difference. Now time for banners; all banners affect the Herald and all units within 12" (which meet the restrictions).
- Blackshields - Dark Banner: All LA(Blackshields) gain Fear and +1 Leadership. All-round solid banner.
- Loyalists - Banner of the Aquila: All models with LA (including the Herald) who are part of a Loyalist force gain +1 WS to a maximum of 5. Solid banner that can be used for either defensive or offensive purposes, as most things are when comparing Loyalists to Chaos.
- Traitors - Banner of the Eye: All models with LA (including the Herald) who are part of a Traitor force add +1" to both charge and run distances AND may re-roll 1's to HIT on the turn they successfully charged, World Eater-style. An extremely aggressive banner, which is usually the case for Traitors. Now go dig the loyalist scum out of their hovels!!! DEATH TO THE FALSE EMPEROR.
- The Herald bizarrely gets both the Rite of Command AND the Support Officer rules, so if you take a Herald he cannot fill your compulsory HQ slot but he HAS to be your warlord (and can't be taken along any other model that also has to be your warlord) unless you also take your Primarch, meaning that extra victory point he concedes for killing him likely doubles due to "Slay the Warlord" objectives. Rite of Command also grants you the Master of the Legion rule meaning you can take a Rite of War with a Herald.
- Playtest Rules: FAQ Feb 19 Do remember that these rules can only be used if both players agree to use them, as they're not official yet. Heralds get Implacable Advance (which is quite good on an Independent Character if you attach him to a non-scoring unit) and Fearless, in addition as of these rules Heralds can take Terminator Armour. Now that this has been made a thing, consider the Herald to be a super-sized version of the Ancient from a Command Squad, and actually a viable HQ choice now. If you're looking for inspiration, consider putting him in squads that aren't normally scoring that you want to be (Tyrant Siege Terminators, Fulmentarus, Quad Mortars, you get the idea) and enjoy a 12" bubble of whatever bonus you're getting based on your loyalty and a fearless pseudo-scoring unit now. Engage maximum troll-face if you throw them in a unit of Iron Circle just to really capitalize on keeping that flag safe...