Section 04

City Progression

Furnace, research order, the Fire Crystal age, and the walls you can't spend your way past.

The Furnace gates everything No building may exceed your Furnace level, and hero levels are capped by it too. If every hero on your roster sits at the same level, that's a wall — not a coincidence — and pouring XP in does nothing until the Furnace moves.

Research order

Growth → Battle → Economy. Two nodes matter more than everything else combined.

#	Node	Why
01	Tool Enhancement	Cuts research time. Every later project pays this back. Compounds over hundreds of upgrades.
02	Tooling Up	Cuts construction time. Same compounding logic. These two are the highest-ROI thing a free account can do.
03	Command Tactics	Extra march queue. Multiplies gathering, beast hunting and rally participation at once — the sleeper pick.
04	Training speed & capacity	Feeds every troop event you'll score in.
05	Healing speed & Infirmary	The difference between wounded and dead after SvS.
06	March / regiment size	Bigger rallies, more castle value.
07	Infantry Defense	First battle node worth having. A tanky front holds the line.
08	Lancer / Marksman Attack	After the front can survive being hit.
09	Gathering speed	Economy — only once timers are already short. Up to +242.5%, the largest single bonus in the game.
10	Resource production	Last. Raw output is the cheapest thing to fix.

The common mistake Blind-researching whatever's next. Spending resources and speedups on low-ROI tech is the most frequent way players stall — the tree is not meant to be completed in order.

Building priorities

Embassy — the most underrated building in the game. Higher levels mean more alliance helps and more time cut per click. In an active alliance that's free construction time daily, and it compounds harder than any speedup stack.
Research Center — gates the two nodes above.
Command Center — march and rally size. Decides whether you can lead rallies at all.
Infirmary — capacity decides how much of your army survives a bad day. Severely wounded troops go here up to capacity; only the overflow dies.
Three troop camps — tier gates.
Warehouse — protects resources from raids. Matters more as your stockpile grows toward FC requirements.

Pause at Furnace 26 Before pushing to 30, level all three camps, clear your research backlog, and rebuild resources. People sprint the Furnace and arrive in the Fire Crystal age with tier-8 troops and an empty warehouse. Arrive with an army instead.

Furnace levels: prerequisites & unlocks

Every Furnace level needs the Embassy at one level below the target, plus one rotating second building (a troop camp or the Research Center) also at one level below. The pattern holds through 30 — so the Embassy is never optional, and pre-levelling the next blocker is always the efficient play.

Furnace	Key prerequisite	Unlocks
8	Infantry Camp 7	Embassy · Arena · Monument · Marksman Camp · Infirmary
9	Embassy 8 · Infirmary 1	Storehouse · Research Center · Lancer Camp
10	Marksman Camp 9 · Research Center	Command Center · Shelters 7–8 · first Formation slot
11	Embassy 10 · Lancer Camp 10	Enlistment Office · Tier 4 troops · meat costs begin
13	Embassy 12 + rotating	Drill Camp (hero XP engine)
15	Embassy 14 + rotating	Hero Gear
16	Embassy 15 + rotating	Frostfire Mine eligibility
18	Embassy 17 + rotating	Beast Cage (pets)
19	Embassy 18 + rotating	Labyrinth (via Command Center) · Daybreak Island dock
20	Embassy 19 + rotating	Mastery Forging
22	Embassy 21 + rotating	Chief Gear
25	Embassy 24 + rotating	Chief Gear Charms
26	Embassy 25 · Marksman Camp 25	—
27	Embassy 26 · Lancer Camp 26	—
28	Embassy 27 · Research Center 27	—
29	Embassy 28 · Infantry Camp 28	—
30	Embassy 29 · Marksman Camp 29	Fire Crystal age · base cost 300M wood, 300M meat, 60M coal, 15M iron

How to read this Prerequisites cascade — the Embassy has its own requirements, which have theirs. So the true cost of a Furnace level includes the whole chain beneath it. Before a push, level the Embassy and the next rotating building first, so the Furnace timer starts the moment you have resources instead of waiting behind a prerequisite you forgot. Costs and times shown anywhere are base values — your construction bonuses cut them substantially.

The Fire Crystal age

Begins at Furnace 30, once your state is old enough — usually around 60 days. Everything changes: the currencies, the costs, and what's worth doing.

Three rules

Don't convert every Fire Crystal into shards. The War Academy needs crystals to raise its own FC level, and Helios research is gated behind that. Convert early and you'll hold shards you can't spend.
Raising a camp's FC level upgrades every troop you already own — automatically, no retraining, no per-unit cost. Highest value per crystal in the whole age and the easiest thing to miss.
Never start an FC upgrade you might cancel. Cancelling mid-way refunds only 50%.

What FC stages cost

Wood and meat are always identical and always by far the largest requirement:

Stage	Wood	Meat	Coal	Iron
FC2	65.5M	65.5M	12.7M	3.3M
FC5	84M	84M	16M	4.2M
FC10	160M	160M	33M	8.4M

A consistent 1 : 1 : 0.2 : 0.05 ratio. Every player in your state hits this in the same order — wood and meat are a universal bottleneck, not a personal failing.

Which buildings take FC levels

Furnace, Embassy, Command Center, Infirmary, and the three troop camps. The Crystal Laboratory produces additional Fire Crystals and later Refined Fire Crystals — check it daily. The War Academy introduces Fire Crystal Shards for T11 research.

The Furnace repeatedly requires the Embassy plus one other progression building, so the efficient play is preparing the next blocker before it blocks you rather than upgrading one building at a time.

The War Academy

Appears in the Fire Crystal age. Three branches — Helios Infantry, Lancer and Marksman — each five levels deep, each unlocking T11 for that troop type. Runs on Fire Crystal Shards and Refined Steel, roughly 13,400 shards per line.

Do one troop line at a time. Spreading across all three means none of them finish. Beyond T11 it gates T12 (Exalted), which needs the Academy around FC5–FC10 depending on the track.

Heroes and the Drill Camp

Hero level is capped by your Furnace. Check the requirement before collecting or buying XP.
Drill Camp runs off your lowest instructor. One hero at 80 next to a fifth at 65 buys almost nothing — level five together.
Don't over-level heroes you'll replace. New generations arrive as your state ages.

The Wish Station

At Fire Crystal Lv. 1 the old Suggestion Box becomes the Wish Station. Completing Wishes earns Wish Sigils, spent in the Wish Shop on materials for 9 entertainment facilities. Each finished facility produces daily rewards at random — Chief Gear, Chief Charm materials, pet and Expert development materials, Hero Gear — and higher FC Furnace levels increase that daily output.

All materials are collectible free through normal play. See the materials guide for the full loop.