yugioh rex raptor deck Speed Duel Ultimate Predators Starter [Sealed Deck] (Pre-Order ships July) – Ryuzaki/Rex - Waking the Dragons

While "Polymerization" is in your GY, your opponent cannot target this card with card effects

Card Type: Effect Monster Card Number: BPT-004 Set: 20022003 Collector's Tins Attack/Defense: 1200/1100 Attribute: Dark Level: 4 Monster Type: Spellcaster Passcode: 17985575 Card Text: As long as this card remains face-up on the field, all Dragon-Type monsters cannot be targeted by Spell Cards, Trap Cards, or effects of monsters that designate a target

The most valuable cards from the Dragon set typically include holographic rare cards, first edition prints, and cards featuring popular Pokemon

Again, this blog factors in both pack price and how cool the cards are