I am confused as to how much Willpower spells cost. If I am, say, a Rank 2 talent Druid, and I want to cast a Rank 2 spell, does it cost me 2 Willpower (ie, does the spell rank determine the minimum Willpower to be spent)? And if I choose to safecast, and cast it as a Rank 1 spell, I only roll 1 dice, but does it still cost me 2 Willpower? And if so, is the base power level for the spell now 1, or 2?
Or is Willpower expenditure always totally up to the caster? Eg, as a Rank 1 caster, can I spend 5 Willpower on a Rank 1 spell?