Rulings

• Mana produced by Somberwald Sage can be spent on any part of a creature spell's total cost. This includes additional costs (such as kicker) and alternative costs (such as evoke costs).2012-05-01
• Mana produced by Somberwald Sage can't be spent on activated abilities, even ones that put a creature card directly onto the battlefield, such as unearth or ninjutsu.2012-05-01
• Mana produced by Somberwald Sage can't be spent on noncreature spells that would put creature tokens onto the battlefield.2012-05-01