Choose roll or fuse
Below Rebirth 4, fusion is mathematically superior. Above Rebirth 4, raw rolls become competitive once daily code allowances are counted.
Fusion recipe chain
Follow the chain: 5x Dull Glow to Bioluminescent, 3x Bioluminescent to Abyssal Echo, 2x Abyssal Echo to Oasis Surge, 4x Oasis Surge to Mythical Tide, and 1x Mythical Tide plus 3x Prehistoric Shell plus 2,500,000 cash to Extinct Leviathan.
Boost timing
Use the 1.5x VIP Training Zone aura-rolling bonus and the daily code allowance together. Stack with the 2x Luck Event windows if the server is running one.