|Card Trader Expense|
Can be used when your Life Points are 1000 or below. Until the End Phase, reduce the Levels of all monsters in your hand by 3. This skill can be used on "Suijin", "Kazejin", and "Sanga of the Thunder," regardless of your remaining Life Points This skill can only be used once per Duel.
Rapid one turn KOs with Des Kangaroo's destruction effect/Eliminating the League followed by a Master of Oz fusion summon.
Very high attack monsters - Master of Oz doesn't fear being turned into defence mode and can ram into monsters without fearing Mirror Wall.
Weak to Guardian Statue/Hane Hane/Gale Lizard - anything that bounces Big Koala/Master of Oz back is going to cause problems.
So thanks to Three-Star Demotion, all the monsters in the deck can be summoned so you should never get a total brick. Three-star demotion is more of a back up plan than anything.
The deck combines easily summonable high attack monsters - Master of Oz and Big Koala with counters to pretty much anything in Eliminating the League and Magic Drain.
Magic Drain counters Black Illusion Ritual, Order to Charge and Enemy Controller taking Master of Oz.
Eliminating the League stops tricky monsters like Barrel Dragon, Dark Magician (Thousand Knives), and Relinquished from getting on the field and lets you see their hand and check if they can counter Magic Drain. All the spell cards in the deck can be discarded - Polymerisation is non-crucial as Hex's effect can summon Master of Oz.
Double Summon is a proxy Polymerisation when combined with Hex's ability - summon Hex + Des Kangaroo/Big Koala in one turn and use the special summon. More versatile than an extra polymerisation as can summon two Big Koalas as well.
We don't need life point gain as the deck doesn't rely on being able to summon Big Koala - it is only a last resort when we don't draw anything else.
This is why we don't run Champions Vigilance as it doesn't work with Master of Oz and is a dead card. We have enough counters with Magic Drain, Enemy Controller and Eliminating the League - which work all the time and don't rely on having Big Koala out.