Supplements

Of all the damage types, fire and lightning seem to get all the best coverage. Maybe it's because fireball and lightning bolt are quantum leaps forward in the offensive arsenals of low-level sorcerers and wizards, or just that there's a limited amount of space in any core rulebook, that an idea like an Ice cleric domain or a Cold wizard specialty that's separate from the more material idea of elemental water is overlooked. But that doesn't explain their absence from rules expansions? Why are there so few new options to keep characters in the cold?