Beastcaller Savant

• WWizards of the Coast2015-08-25
  Official Ruling
  Mana produced by Beastcaller Savant can be spent on any part of a creature spell’s total cost, including additional costs (such as kicker costs) and alternative costs (such as dash costs). It can’t be spent to pay the costs of abilities of creatures you control.
• WWizards of the Coast2015-08-25
  Official Ruling
  Mana produced by Beastcaller Savant can’t be used to activate an ability or cast an instant or sorcery spell that creates creature tokens.

Rulings via Scryfall