Mordan's Vault

A feruchemist can store skills in quintenium/copper.

While storing, the feruchemist is treated as having fewer ranks in a given skill or a lower Base Attack Bonus (BAB), to a minimum of 0. Ranks in a Knowledge skill cannot be stored in quintenium/copper. Regardless of the number of ranks they are treated as having, if the feruchemist normally has at least 1 rank in a skill, they are still treated as being trained in that skill.

While tapping, the feruchemist is treated as having more ranks in a given skill or a higher (BAB), to a maximum of twice their normal. If a feruchemist without ranks in a skill taps a number of ranks from an unkeyed metalmind, they do not become trained in that skill.

Each metalmind can only store a ranks from a single skill and cannot store both skill ranks and BAB.