Half of which came from WAR and ruined different formats in one way or another
Like most Magic: The Gathering cards, the value of Sea Legs depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Rivals of Ixalan)
I hope this breakdown was helpful in picking your Starter Deck
Losheel, Clockwork Scholar Losheel, Clockwork Scholar gives artifact creature decks some real oomph thanks to the combination of card draw and protection in combat, which Ive found particularly useful to allow Thopters to attack to trigger cards like Bident of Thassa
For example, if you control a creature with hexproof from blue and another creature with hexproof from black, you create a single Blood token
Purphoros, on the other hand, lets you cheat on mana costs, too, giving you a burst of speed