Looking to be semi-competetive with Sons of Horus though I realize that the legion's ruleset has serious limitations. Trying to both play to the legion's strengths and have multiple threats/ lots of scoring units to rack up VPs in certain missions. At the moment, list is rather weak in terms of anti-armor. Also, toying with the idea of shifting things around a bit to replace the Typhon either with Horus or with a Falchion.
-Yeah it's not bad, I like the Legion rules myself (hence I have 2 armies of the 16th), but this one is an interesting one for me. I'd say that it's not so much anti-armour as something Lautrec mentioned, anti terminator/monsters. You have a respectable enough set of scoring units, but it's a little light on bodies for someone like me, and not an enormous amount of redundant role diversity in case certain portions get knocked out. I'd also be very worried about things like aircraft.
LoW: Typhon w/ Armored Ceramite 
-Not bad, it's pricey and it'll attract a lot of fire so watch for any mirror Lightnings which will ruin your day.
- Maloghurst  -- Joins Tactical Support Squad in Rhino
-yep, totally works. Mal's usually seen as a top tir choice, but here's the thing: he's top tier because he allows vets, which you're not using. Which I'd try to work some points in for, even just to replace the tacs with a blank veteran tactical unit. The extra attacks and kit are worth it along with their specialization.
- Primus Medicae w/ Terminator Armor  -- Joins Justaerin in Spartan
-This is pricey. Not terrible but in this point environment it feels excessive: there's no close combat hero to help your troops out of a jam and it goes to make that Justarian unit ENORMOUS. So if they get hung up by a thrown track or struck against a dreadnought, we're talking about more than 1/3rd of your points in 1 place.
- 9x Justaerin (5x Pairs of Lightning Claws; 4x Power Sword & Combi-Bolter) 
-Lautrec has this covered, it's the elephant in the room. It you absolutely can, you NEED a few chainfists, power fists, or the like. I'm not a fan of axes with Justarians are it doesn't often give you anything extra with our legion, but they need some AP 2 and they absolutely need some way to deal with dreadnoughts and characters that will dice them all game long.
Dedicated Transport--Spartan w/ Armored Ceramite 
-This+Typhon feels like a lot of heavy armour in 2.5K, especially as it's all loaded up. Though at least I don't have to see a flare shield on top of it all.
- 1x Apothecary (Jump Pack) 
- 15x Reavers (Jump Packs; 4x Power Swords, 10x Chainaxes; Sergeant w/ Power Sword & Melta Bombs) 
-Everyone will say what they want about Reavers, I personally love them but they're expensive and tough to use at times. Might want to swap out some of the power swords for axes or fists for the same reason as the Justarian, and sergeant with artificer armour is usually encouraged.
- 10x Tactical Marines (Vexilla; Sergeant w/ Power Sword; Rhino Transport) 
-I'm good with this, seriously it's fine. Vexilia might be overkill compared to artificer armor sergeant.
- 5x Tactical Support Marines (4x Volkite Chargers; Sergeant w/ Combi-Plasma; Rhino Transport) 
-All good, no issue. Combi-plasma might seem a little weird but I like units like this. That said, Mal's going here, right? Well, it limits their speed and flexibility pretty hard as they become less an assault unit. It might be good if you could see about snagging a few points and 'upgrading' them to Calivers which really make the difference with their better range, st.6, and first turn benefits.
- Primaris Lightning Strike Fighter (2x Kraken Missiles; Battle Servitor Control) 
-All good, it'll crack open a few heavy tanks and the like. Just watch for AA fire.
RoW: The Long March --- Total Points: 2500
-This one I'll admit I'm almost surprised with. It's a great rite, but there's not a lot of places to reroll those 1's, not enough guns to count or heavy weapons that take advantage of the Relentless, it helps mid and backfield, but I'd think that the Javelin or Sicaran would be more useful for something like this. Going out a bit, Horus can work at 2.5K but I'm not sure like this. The Falchion I think is waaaay over-specialized here.
Lots of other possibilities--like I said, could run this with Horus or a Falchion instead, might switch something out for javelin speeders or Sicaran-platform tanks (I have a battle tank and an arcus). The idea is, though, everything is mobile, everything scores, everything benefits from SoH special rules.