List the title of the episode with stars greater than the 70% of average stars of all episodes.
stars greater than the 70% of average stars refers to stars > multiply(avg(stars), 0.7)
SELECT DISTINCT T1.title FROM Episode AS T1 INNER JOIN Vote AS T2 ON T2.episode_id = T1.episode_id WHERE T2.stars > 0.7 * ( SELECT AVG(stars) FROM Vote );