Strengths:
7thlevel fast flyers with non-retaliated attack, although pretty expensive.
Excellent 3rdlevel monster.
Castle gate! - In larger maps it's very good!

Weaknesses:
Four armies are walkers - higher losses in sieges.
Measly shooter that is often dangerous for his own buddies. (Never press Auto in battles ;-))

Army evaluation:
Imps 2/3/4/1-2/5/50
Familiars 4/4/4/1-2/7/60, drains 20% of enemy's spent mana
Maybe they should be called wimps instead, coz they definitely are... However, the familiars are pretty fast and their special sometimes comes handy. And one more good thing - AI loves to kill them...

Gogs 6/4/13/2-4/4/123
Magogs 7/4/13/2-4/6/175, area attack
The faster magogs are useful with their special (especially against heroes with six or armies and some war machines ;-)), but if the enemy manages to put all stacks adjacent to yours, they are useless ;-)

Hell Hounds 10/6/25/2-7/7/200
Cerberi 10/8/25/2-7/8/250, no retaliation, attack enemies adjacent to target hex.
One of the best 3rdlevel monsters, Cerberi with their boosted numbers and non-retaliated wide attack are a great offensive weapon.

Demons 10/10/35/7-9/5/250
Horned Demons 10/10/40/7-9/6/270
They're tough, they're cheap, they can be raised almost like skeletons. Do you need anything more?

Pit Fiends 13/13/45/13-17/6/500
Pit Lords 13/13/45/13-17/7/700, can raise demons from slain allies
Although costly, they make good fighters and their special comes handy when your familiars or gogs have been crushed. Since the demons are raised permanently, this special can be expanded to great effects.

Efreet 16/12/90/16-24/9/900, immune to Fire Magic
Efreet Sultans 16/14/90/16-24/13/1100, immune to Fire Magic, FireShield
Very mobile and dangerous flyers. Good for magic combos. AI targets them often.

Devils 19/21/160/30-40/11/2700 + 1m, no retaliation, 150% against angels, reduce enemy luck
Archdevils 26/28/200/30-40/17/4500 + 2m, no retaliation, 150% against angels, reduce enemy luck
Very effective 7thlevel units, although not as tough as we would like them. Will take out angels any day of the week ;-), but will get kicked badly by Archangels.

Upgrading priorities:

• Familiars: Lowest. Used as cannonfodder. Upgrade if you're gonna have strong spellcasters as opponents.
• Magogs: Moderate. In early exploration, the fireballs work wonders against flyers and walkers.
• Cerberi: Highest. The best upgrade of Inferno castle.
• Horned Demons: Low. I don't use them if I don't have to.
• Pit Lords: Same as Demonds.
• Efreet Sultans: High. +4 speed along with FireShield make them great anti-shooter army.
• Archdevils: High, since upgraded can move almost across the whole battle field (and play last in waiting and first afterwards, allowing two consecutive strikes with no retaliation.)

Castle building in the first week:

Day 1:	Town Hall	2500g
Day 2:	Hall of Sins	1000g + 5o
Day 3:	Kennels	1500g + 10w + 5o
Day 4:	Demon Gate	2000g + 5w + 5o
Day 5a:	Mage Guild	2000g + 5w +5o
Day 6a:	Fire Lake	4000g + 10o + 3gms
Day 5b:	Hell Hole	3000g
Day 6b:	Cages	1000g
Day 7:	Citadel	2500g + 5o

Crucible as 1stlevel dwelling assumed present. If it's not present, we are forced to take the b) variant, shifted one day and therefore without cages. (or we could skip TownHall).
The a) variant is for the gold-richer scenarios, while the b) variant is for those where gold is scarce. The b) variant can be made even cheaper, skipping Hell Hole and instead upgrading Kennels or Hall of Sins, with the other upgrade done on day1 - and the army of magogs and cerberi set for exploring.

Resource summary:
For a) variant, you'll need 20w, 30o and 15500g, which leaves us (20000 + 7000 - 15500) = 11500g for Day 1 to spend on troops. Efreet will cost 5x900, cerberi upgraded on day1 will take 1500 + 12x250, gogs 20x125 - total 11500. (well, four less gogs and we can get a spellbook ;-)). In this variant, the trouble is the 10 extra ore.
The b) variant will take 15w, 15o and 13500g (with hellhole skipped in favor of kennel upgrade 11500g). That leaves 15500g for shopping on day1 - where it would be 1000 + 20x175 for magogs, 15x250 for Cerberi and 7250 gold left for demons/imps or saved for castle expansion. If we get the hellhole and recruit pit fiends for 7x500, we'll still be left something about 2000g.
There could be even more-saving variant - build townhall, hall of sins, kennels, cages, upg. kennels, upg. hall of sins, citadel, upg. crucible - and recruit all familiars, cerberi and gogs. That would save most of the resources for raising money generator early in second week and possibly getting either hellhole or firelake by the end of that week.

Second week strategies:
City Hall should be the first priority, if you can scrap enough wood. (By day 3 of first week you should have chosen one of the minimal variants, if it was clear that wood would be scarce.)
Later, you should start getting some mercury. Resource silo is costly, but pays back in longer games.
The ideal building schedule would be: day1: upgrade of kennels/hall of sins, followed by marketplace, blacksmith, (mageguild if saving variant was chosen), cityhall, horde dwelling, castle. In the next week, you should wait for the Capitol, spending nothing.

Troops cost weekly (with castle):
Without 7th level: 19090
With 7th level: 28090
With one castle producing 14000/week, inferno players are quite used to leave demons and imps at home, possibly also either hellhounds or pit fiends, especially if they're not upgraded yet. Capitol at 28000/week will just about support full army production.
HPs grown weekly 1635 (plus 400 in archdevils) at 11.68 g/HP (13.80)

Benefits:

• Birthing Pool: +8 crucible production. Early or never.
• Blacksmith: Ammo Carts - never bought any.
• Brimstone Clouds: +2 SpellPower when under siege (good one!)
• Cages: +3 kennels production - a must have.
• Castle Gate: Town Portal among Inferno Cities with Gates. Great, yet costly!
• Order of Fire: +1 Spell Power for every visiting hero. Not bad.
• Resource Silo: one mercury/day. Get it ASAP.

Strategy
Unless you get +10 ore, you'll be forced to one of those cheaper variants, but don't worry, they're not that bad. Wood source is quite important, but the extra wood will be needed during second week.

Forces combination:
Magogs, Cerberi and Efreet Sultans are a good expeditionary force, for longer campaings best accompanied by Pit Lords or Horned Demons to do the protective work. Use Efreet to lure enemies together and then try some area spells from Fire School. (Fireball, Inferno). In case that you get Armageddon somewhere, have a secondary hero close by, so that you can temporarily discard magogs and cerberi, launch the nukes and then continue...
Demons and Familiars are good for castle defense - familiars will attract the enemy fire, while Demons will kick some butt.
If you'll have good forces of Devils and Efreet, you might give all those Magogs (probably not any much due to castle towers' fire) and Cerberi to some secondary hero to enjoy those few extra movement points from units with speed 11+ for the main guy. However, get used to some losses in castle defenses, then.
Take familiars with you to long journeys against spellcasters or generally strong opponents - AI will spend a lot of firepower attacking them and this may prolong lifetime of your main forces by some 5 battles.
When using Magogs, watch out for war machines on enemy side. They can be targeted and if six or seven army slots are filled on the enemy's side, aiming at a war machine causes TWO adjacent armies to get hit. You might even want to cast Haste on the Magogs, if it'll help them to play before these two units can move.
Using pit lords is simple and effective. I recommend waiting a few weeks to accumulate some decent number of them and then rush out. Try to get any low-level critters you can, recruit at castles, empty all dwellings and in battles with anything moving let the weakies perish and then be raised into demons! This is even better than necromancy, since the demons are far better than bones.
You might even sacrifice your imps for this reason. But it works best with diplomacy - you could even have a secondary hero get diplomacy from a hut/university and with a force of pit lords and demons persuade willing stacks to join and sacrifice them in battles with the unwilling ;-). However, it takes some practice to force a particular stack to die...

Heroes:
Demoniacs: Calh is a gog fan and has Archery. Fiona is a good Scout and also handles hell hounds well. Ignatius is good with imps and has Tactics and Resistance. My favorite if Pyre (Logistics and Ballista specialist.) Octavia yields gold - a good secondary in early game. Nymus boosts Pit Lords and has Offense! If you're in for the demon summoning, take Marius that will make them better.
Heretics: Ash has BloodLust (a good candidate for Fire Magic). Ayden has Intelligence - a good long-runner or castle defender. Other good ones: Olema - good for sieges. (Ballistics, Weakness). Xyron, Xarfax and Zydar make good Fire spellcasters (Fireball, Inferno and Sorcery, respectively).

Skills important for the troops and strategy:

Ballistics could be needed, since you have three tough walkers, of which usually cerberi and pit lords will be used in long campaigns.

Since 6th and 7thlevel are flyers, you could also profit from Armorer skill, because these two armies will be under great strain, if they engage in battles behind castle walls.

Sorcery and Expert Fire Magic for Heretics is extremely recommended, but either Air or Earth is a must - you'll either need the oponent to slow down, or your troops to hurry to use those potent attacks.

Unit	A	D	HP	Dmg	Sp	$$	AdjD	Dm/g	grow	weekD
Familiars	4	4	4	1-2	7	60	1.32	2.20	38	50
Magogs	7	4	13	2-4	6	175	2.82	1.61	16	45
Cerberi	10	8	25	2-5	8	250	3.50	1.40	13	46
Horned Demons	10	10	40	7-9	6	270	8	2.96	8	64
Pit Lords	13	13	45	13-17	7	700	17.25	2.46	6	104
Efreet Sultans	16	14	90	16-24	13	1100	26	2.36	4	104
Archdevils	26	28	200	30-40	17	4500	63	1.40	2	126