You can visit any Barbarian Guild leader, and STUDY them to learn the syntax.
ASK <guildleader> ABOUT BERSERK to get a list
CHOOSE <abilityname> to learn it
"I have no data yet. It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories instead of theories to suit facts."
- Sir Arthur Conan Doyle, Sherlock Holmes