There are a few builds centered around Fires of Invention that don't play very many double-costed spells so it would make sense that Jegantha might do some work there...play it as one of your two spells after your Fires turn and then use all of that mana to activate Kenrith, the Returned King or Cavalier of Flame triggers
It was the deck's real in-archetype tuner, making it the ideal way to summon all the big level 7 and level 10 synchros the deck keeps in its extra deck
Thousand-Year Elixir Thousand-Year Elixirs a handy tool for decks full of creatures with tap abilities
Getting to reset the board often results in cards that offer powerful card advantage and stabilization, but the best board wipes are asymmetrical ones that devastate your opponents while leaving your board untouched
The ubiquity speaks to its fundamental power level players recognize that explosive mana advantage translates directly into winning games
The United States terms describe a right to request card purchases under the program, not the Japanese collaboration-menu bonus