[c]Colossus Hammer[/c], [c]Gravity Well[/c], and [c]Mu Yanling, Sky Dancer[/c] can all cause a creature to lose flying
If you cant accurately spot fake cards not in person, theres a pretty good chance youll get burned here, too
As far as which has the highest equip cost, Belt of Giant Strength is technically the one with the highest, but it varies depending on the creature it targets
Galadriel's Beautiful Artwork Contrasts With Her Lackluster Mechanics According to Tolkien's work, Galadriel is one of the most intelligent and powerful elves on Middle-earth
Regardless, merfolk of any MTG plane consistently support their creature type, be that as your classic Lord of Atlantis or cards like Silvergill Adept and Deeproot Elite that demand a shoal of merfolk to support them
But for a 5-mana commander, Id prefer a card that stands on its own and doesnt require other cards to do things after it enters