To do that, we developed a workflow that asked concept artists and card artists to pull hallmark character designs from Yoshitaka Amanos original (and legendary) concept art, the original FFVI sprites, and the FFVI Pixel Remaster character portraits, to synthesize the most consistent elements of each characters design into something new. We also encouraged our artists to punch up finer details and explore elements where they thought they could push (fabric, patterns, textures, etc.) Then, we would meet with the Final Fantasy VI review team, and they would give us feedback on what core elements they wanted to preserve and what new elements they were excited about
Each Synchro Monster lists its required Synchro Materials in the first line of its card text
In total, there are seven rarities on offer in this set, with the quarter century secret rare being the most desirable, of course, and the price tag definitely attests to that
The answer is the Green Packs
[1] During the End Phase, if a monster has been destroyed by battle this turn: You can Special Summon this card from your hand or GY, then if "Invincible Demise Lord" has been destroyed by battle this turn, this card's ATK becomes 3000, also it cannot be destroyed by effects