In terms of game design, merfolk have been treated as sea creatures in the broader sense
While the aggressive cost of is really good, the cost to copy spells is pretty steep if you have enough targets
4) Original Rayquaza Card: Rayquaza EX #97 This Rayquaza card was released with the Dragon set, making it incredibly old
I think Panharmonicon and Elesh Norn, Mother of Machines are worthy upgrades
You can run cards like 10-cost Monkey D.Luffy and 10-cost Kaido & Linlin
With Regenerate, you essentially set up a replacement effect in the form of a "regeneration shield", so to speak, before the Creature would be destroyed, and once that's done, Regenerate replaces the next instance of the destruction of said Creature with: tapping the Creature, removing damage from it, and removing it from combat