Benthic Biomancer Another merfolk all-star, Benthic Biomancer goes in more decks, including counter shenanigan decks like Chisei, Heart of Oceans or Goldberry, River-Daughter
Earlier editions of TCGEditor would've given you some of them as required files
Absolute Zero Monsters(15): 3x Deep Sea Diva 3x Elemental Hero Neos Alius 3x Elemental Hero Ocean 1x Elemental Hero Stratos 1x Elemental Hero Woodsman 3x King of the Swamp 1x Mobius the Frost Monarch 1x Treeborn Frog Spells(13): 1x Burial from a Different Dimension 1x Dark Hole 1x Future Fusion 2x Miracle Fusion 1x Monster Reborn 2x Mystical Space Typhoon 3x Polymerization 1x Pot of Avarice 1x Reinforcement of the Army Traps(11): 2x Bottomless Trap Hole 1x Call of the Haunted 2x Dimensional Prison 2x Dust Tornado 1x Interdimensional Matter Transporter 1x Mirror Force 1x Solemn Judgment 1x Torrential Tribute 3
In addition to being basically a Fusion-Equip-Spell Card, the card also has a die roll effect where when the Monster it's equipped to battles another, you roll a 6-sided die and your opponent's Monster will be banished for that many of your opponent's turns until the first Standby Phase after the last turn of the effect
The rarest: Prism, Secret, and Jumbo Among the 309 cards in Parts 1 and 2, 24 Prism cards (holographic) are the most sought-after pieces