1. Pertaining to the Bible, the sacred text of Christianity.
2. (slang) Characterizing harsh, serious treatment.
3. (slang) Sexual. Used in the phrase, "in the Biblical sense", esp. applied to the use of the verb "know".
(def. 2): Tony said if we don't get the job done by Friday, he's going to have to get biblical on our asses.
(def. 3): Yeah, I'm really glad I got to know Lisa. Heh, in the biblical sense.
The replacement for the word "epic." Epic got old. It got boring listening to people say "epic win!" and "epic fail!" So, it only makes sense to replace it with a new word, and the most appropriate word would be "biblical".