Step 1. Normal Summon Deep Sea Diva, Special Summon Neptabyss and use its effect to send Atlantean Dragoons from Deck to the graveyard and add Atlantean Dragoons from Deck to hand. Using Dragoons' effect, add Mermail Abyssmegalo to your hand
Step 2. Special Summon Mermail Abyssteus from hand by discarding Atlantean Dragoons. Use Abyssteus to add Mermail Abyssgunde and Dragoons to add Atlantean Heavy Infantry from your deck to your hand
Step 3. Use Deep Sea Diva and Neptabyss to Link Summon Mermail Abyssalacia
Step 4. Special Summon Swap Frog by discarding Mermail Abyssmegalo, and use its effect to send Ronintoadin from the deck to the GY. Use Swap Frog's effect to return it to the hand and discard Mermail Abyssgunde to special summon it, sending another copy of Swap Frog from the deck to the graveyard
Step 5. Use Abyssgunde's effect to summon Abyssmegalo from the the Graveyard
Step 6. Summon Ronintoadin from the Graveyard by banishing Swap Frog, then use Swap Frog and Ronintoadin to Xyz summon Toadally Awesome, then use Abyssteus and Abyssmegalo to Xyz summon Mermail Abyssgaios