Fullmetal Alchemist Brotherhood: Alchemy System — Core Mechanics and Rules

Fullmetal Alchemist: Brotherhood has one of the most internally consistent magic systems in anime, built on a few core principles: **Equivalent Exchange**: The foundational law — "To obtain, something of equal value must be lost." Alchemists rearrange existing matter rather than creating something from nothing. **Three Steps of Transmutation**: Comprehension (understanding a material's structure), Deconstruction (breaking it down), and Reconstruction (reshaping it). Alchemists need genuine understanding of chemistry and physics. **Transmutation Circles**: Geometric patterns that channel energy and direct reactions. Most alchemists must draw these. Ed Elric can skip this by clapping his hands to form a circle with his body — a consequence of having seen the Truth at the Gate. **The Gate of Truth**: Human transmutation (attempting to resurrect the dead) is the ultimate taboo. It always fails because a human soul can't be equivalently exchanged. Those who attempt it are dragged before the Gate, gain immense knowledge, but lose something precious — Ed lost his leg (then his arm to save Al), Izumi lost internal organs. **The Philosopher's Stone**: Appears to break Equivalent Exchange but actually doesn't — it's made from compressed human souls. The exchange still happens, just with lives as fuel. **Energy Source**: Alchemy in Amestris is powered by tectonic energy from the earth's crust, channeled through a nationwide transmutation circle. This contrasts with Xingese alkahestry, which draws on the "Dragon's Pulse" — energy flowing through the land, similar to chi/qi concepts. The system's strength is its internal consistency — the limitations directly drive the plot rather than being arbitrary restrictions.