Fire Crystals & Refined Fire Crystals

Past building level 30, your core buildings stop costing just Meat, Wood, Coal and Iron: each Fire Crystal level (FC1 → FC10) also costs Fire Crystals, and from FC6 on, Refined Fire Crystals too. Fire Crystals are the resource you'll keep running short of; Refined Fire Crystals are the one you can't simply buy more of, because you make them yourself — at a weekly limit.

This guide puts numbers on both. Every figure comes from the verified data the Building calculator and the RFC simulator use.

What the Fire Crystal levels cost

Taking each building from its first Fire Crystal level to FC10:

The Furnace is by far the most expensive: 11,610 Fire Crystals and 870 Refined Fire Crystals on its own. All eight buildings together need 39,694 Fire Crystals and 2,954 Refined Fire Crystals. The War Academy has no FC1 — it first appears in the Fire Crystal era, starting at FC2.

Plan exact steps — including the in-between sub-levels and each building's prerequisites — with the Building calculator.

Refining: the Crystal Laboratory

Refined Fire Crystals come from refining Fire Crystals in the Crystal Laboratory. Each refinement costs Fire Crystals and returns a random number of Refined Fire Crystals. The rules that shape everything:

• 100 refinements per week, in 5 tiers of 20. Each tier costs more Fire Crystals per refinement — from 20 in tier 1 to 160 in tier 5 — but shifts the odds toward bigger results.
• One half-price refinement a day (50% off), at whatever tier you're on — 7 per week.

Why later tiers cost more per crystal

The last column is the one that matters. Higher tiers give more Refined Fire Crystals per refinement, but not enough to keep up with their price: a tier-1 refinement costs about 13.8 Fire Crystals per Refined Fire Crystal, a tier-5 one about 43.1. So each tier you move into makes your Refined Fire Crystals more expensive.

Using all 100 refinements costs 9,200 Fire Crystals at full price and returns about 279 Refined Fire Crystals on average.

That gives you a simple rule: refine as far as your Fire Crystals comfortably allow, starting from the cheap tiers, and stop when the next tier's price per crystal is more than you want to pay. Since the weekly count resets, the early tiers are always the best value — don't skip a week of them.

Spending the half-price refinement well

The daily discount saves the most where refinements cost the most, but you can only use it on the tier you've reached. So the usual plan trades one cheap discount for six expensive ones:

1. Do the bulk of your refinements on one day, starting from tier 1. That day's half-price refinement lands on a cheap tier-1 one — the price of the plan.
2. On each of the other days, do just one refinement — the half-price one — which now lands on a higher, more expensive tier, where half off saves far more.

The RFC simulator builds this plan for you for any number of refinements, shows the Fire Crystals per Refined Fire Crystal you'll pay, and can roll a simulated week to show how far luck can swing the result.

How long the big upgrades take

At 279 Refined Fire Crystals a week on average (all 100 refinements), the Furnace's 870 take about 3.1 weeks of refining, and every building together about 11 weeks. Refining fewer than 100 a week stretches that out — so decide which buildings matter most to you (usually the Furnace first, since it gates the others) and point your Refined Fire Crystals there.

Checklist

1. Refine every week — at least the cheap early tiers.
2. Use the daily half-price refinement every day.
3. Stop where the price per Refined Fire Crystal stops being worth it.
4. Spend Refined Fire Crystals where they unlock the most, Furnace first.