Alchemy Furnace ★★★

Taken all the way down to base materials, one Alchemy Furnace is 3 crafting steps deep and needs 4 intermediates — Darksteel Rivets ×4, Darksteel Plate ×2, Wolfram Ingot ×1 and 1 other — which resolve to 6 distinct raw materials totalling 29 units, plus 48 crystals.

That bill outweighs 10,170 of the 13,602 recipes tracked here and 1,028 of the 1,441 Armorer ones, and 337 recipes nest deeper.

Only 3 of those crystals go into the final step; the other 45 are burned by the intermediates, so the real crystal cost is 36 Fire Crystal, 6 Ice Crystal, 2 Earth Cluster and 2 other kinds.

The chain crosses two disciplines — Armorer to Lv 50 and Blacksmith to Lv 50 — so no single class can finish it unaided.

3 of the 6 raw materials come out of the ground, and 2 of them are time-gated: Darksteel Ore (1:00) and Ferberite (3:00). The widest gap between consecutive opening times is 22 Eorzean hours, about 64 real-world minutes.

Of the intermediates, Darksteel Nugget has the widest use: 121 recipes call for it, spanning seven of the eight crafting classes.