The Psykter was used to hold wine during the festivities. It was placed inside a Krater filled with ice or snow to keep the wine cool. Servants would ladle wine out of the Psykter and pour it into a Kylix.
The Greek playwright Euboulos listed Dionysus’ rules for proper drinking at a Symposium:
For sensible men I prepare three Kraters: one for health, one for love
and pleasure, and the third for sleep.
After the third one is drained, wise men go home.
The fourth Krater is not mine because it belongs to bad behavior.
The fifth is for shouting, the sixth for rudeness and insults, the seventh
for fights,