The Athena OTK is achieved by the effect of "Honest" and "Athena", while you have "Ultimate Offering" on your side of the field. While you will pay 500 Life Points each time you summon "Honest", your opponent will take 600 points of damage, so by doing it 14 times, your opponent will have lost 8400 points of damage, while you have lost only 7000. This OTK is not currently possible in Advanced Format because "Ultimate Offering" is Forbidden.