Drought
Ice Age — uncommon
Enchantment
Drought rulings:
2016-06-08: Activated abilities contain a colon. They’re generally written “[Cost]: [Effect].” Some keywords are activated abilities and will have colons in their reminder text.
2008-08-01: A hybrid symbol that is both black and another type is a black mana symbol, regardless of what cost is paid for it.
2004-10-04: You have to sacrifice a Swamp for each black mana in the activation cost. If you use Pestilence with , that’s 4 activations with each so you sacrifice 4 Swamps.