First Penguin has added more consistency to WATER decks, as you can discard 1 card to reveal 1 WATER Synchro Monster in your Extra Deck and add a WATER monster from your Deck to your hand with the same Type but 1 Level lower
With cards like Powerful Energy +20 damage and Aurora Energy counts as any Basic Energy Lugia and Archeops full power is released
Removal interacts with mutate spells strangely If your opponent casts a creature for its mutate cost and you remove the creature it was mutating onto, the mutating creature spell doesn't fizzle
I wouldnt have played Ancient Box if I didnt bring the top 20 decks in format stored in my couple of Omnihives that I have from Ultimate Guard which you can check out here
Hydreigon Mega Absol ex Using only Dark energy, evolve Deino into Hydreigon to be your main damage dealer
More importantly, those will be 5/5 elemental creatures when they get back, so for just 7 mana, you get to add 15 power and toughness to the board