Ojamas work flawlessly. Don't use land of the ojamas skill. Just put ojama country in the deck. Last turn, put king and knight in attack position, activate field spell, vassal, unionn att, and ama.
Not entirely sure how consistent it is but it does work if you can get either of the fusion out before Mai gets a full field of monsters. I got 7,000-7,500 duel score with this so far.