Sixteen Ingredient Vials (4 ingredients × 4 vials) are shuffled and placed face down on the table.
On your turn, in order:
At the start of your turn (from the second one on) you can declare the session over. It also ends when all the Seals have been placed.
Shared goal: gather each ingredient into a single group of connected vials, without ever telling each other what you saw.
Score (only if the Great Work succeeds): +5 per Seal left in the deck, +2 per Seal revealed but not placed, +1 per Seal placed on the right ingredient.
When playing with you, AI alchemists use Seals literally: a Seal says exactly “this vial is one of these colours”. They don't place vague Seals on vials you've never seen, nor Seals on vials you've already inspected, and they keep them aside during the first turns.
Among AI alchemists only (Training page) they use a convention instead: ingredients shared with the other Seals in reserve are ignored. On the table, the band that counts has a ★.