New the Ret, after some advice

Here's my opinion for what it is worth. I strongly advice starting with well established casters, models and units. With that in mind, here's a list of things you should look to have according to what you listed in your post.

Warcasters
Vyros2: You named him, he is an incredible caster, especially in Forges of War
Rahn: You named him, strong caster, might not be the best in the current meta, I lack real game experience with him so can't really help you out here.
Issyria: She's one of the best casters in the faction, she is just such a good generalist.
Kaelyssa: She's the caster that is the most involved usually. She has an incredible feat and allows a really fun hit and run style. I suggest you read the guide I wrote on her if you want to know a little bit more.
Helynna: She comes with the battlebox, she's a really fun caster to play and can run some really fun jack heavy lists. Once again, I wrote a guide on her, I suggest you start there for more information. She also happens to come in the Battlebox which is one of the best out there in terms of model usage.

Warjacks
3 Shyeel kit with magnets if you can, otherwise, at least 2 Manticores and one Hydra. The Phoenix is becoming pretty rare.
1 Vyre kit with magnets if you can, otherwise, at least one Banshee.
Up to 5 Griffons. Don't get more, but you'll use up to 5.
1 Aspis
2 Chimeras
Discordia
Imperatus
Helios/Hyperion kit

Units
1 unit of Sentinels
1 unit of Halberdiers (more if you like the Defenders of Ios theme)
2 units of Battle Mages if you want to play Rahn
1 unit of Mage Hunter Strike Force with Eyriss3 and the Commander

Solos
3 Arcanists
1 Artificier
1 Lys Healer
Elara1

It's a big list, I can get more specific depending on which casters you plan on playing. Let us know what is in the lot you just acquired, we can dojo from there.

I will second Mangled's model recommendations above, if you buy what he recommends you will have the foundation for almost all competitive lists. That is currently evolving as our new themes from the forces book just dropped and people are still seeing how viable we can Make Defenders of Ios and the others. The 2017 Steam roller rules as well as the Battle engine CID are still ongoing and some stuff is in the air until those are finalized. Buy the battle box unless you just have everything in it already from what you got off your mate. Helynna is a great caster to learn the game with and you will use all the models pretty regularly going forward. The Chimera is our go too cheap arc node, you will use Griffons and lots of them especially if your playing Vyros 2, and the Manticore is our go to utility heavy. I will say the Battle box is just a Manticore and not a kit, I just turned it into Discordia since its an upgrade kit and some of the bits are too small to magnetize practically so I ended up just doing a full assembly on Disco, but since its one of our most used Character heavy its not a loss and it still looks Manticore enough that you can downgrade it with no problems. His list is not gonna cover everything but you should be able to fill out to taste and unless your very focused on playing only 2 lists with little change up you will find your self reaching for what he recommended on a regular basis.

I'm still not convinced that the theme lists are the end all be for list design in the game. People will often argue that taking a model or unit isn't worth it because of the free points your missing out on. But you need to remember that the free points and extra benefits are at the expense of a more optimized list design, or are pigeon holed into a list with built in flaws, such as very limited model selection and lack of option for pathfinder. Particularly for someone just starting out with a faction.


I've found that vyros works well when running heavies and has a very good kit for most styles of lists. I personally like using heavies along side lights and a unit or two.

I do think that building into the various factions jack/beast themes is at the very least worth looking into. Primarily due to the fact that heavies cost less than units do. Particularly if the battle box has heavies AND one of the lights are useful for many casters in multiples (ret is one that of them) it Ian worth getting two of them and a couple heavy kits and magnetize.

War Room Army

Retribution of Scyrah - Vyros 2 Theme

Theme: Forges of War
3 / 3 Free Cards 75 / 75 Army


Vyros, Incissar of the Dawnguard - WJ: +27
- Sylys Wyshnalyrr, The Seeker - PC: 0
- Griffon - PC: 8
- Griffon - PC: 8
- Griffon - PC: 8
- Griffon - PC: 8
- Griffon - PC: 8
- Helios - PC: 34 (Battlegroup Points Used: 27)
- Imperatus - PC: 22

House Shyeel Magister - PC: 0
House Shyeel Magister - PC: 0
Arcanist Mechanik - PC: 2
Arcanist Mechanik - PC: 2
Arcanist Mechanik - PC: 2


THEME: Forges of War
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GENERATED : 05/15/2017 15:14:20
BUILD ID : 2039.17-03-16


War Room Army

Retribution of Scyrah - Rahn

Theme: No Theme Selected
75 / 75 Army


Adeptis Rahn - WJ: +26
- Sylys Wyshnalyrr, The Seeker - PC: 4
- Phoenix - PC: 18 (Battlegroup Points Used: 18)
- Chimera - PC: 8 (Battlegroup Points Used: 8)
- Discordia - PC: 18

Arcanist Mechanik - PC: 2
Arcanist Mechanik - PC: 2
Eiryss, Mage Hunter of Ios - PC: 7

House Shyeel Battle Mages - Leader & 5 Grunts: 10
Dawnguard Sentinels - Leader & 9 Grunts: 18
- Dawnguard Sentinel Officer & Standard - Officer & Standard: 4
- Soulless Escort - PC: 1
Stormfall Archers - Leader & 3 Grunts: 9


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GENERATED : 05/15/2017 15:15:54
BUILD ID : 2039.17-03-16

I ran this exact list the other week, but swapped a Griffon for a Chimera in order to turn on casting Lock the Target, no regrets at all. Just a suggestion!