Well, today I noticed that there's another spell "missing" from B/X. It's a tad bit more debateable I guess, but here we go anyway. If you turn to page X49, you'll find the Staff of Power which (among other things) can be used to cast Cone Of Cold. And sure enough, there's no spell with that name in B/X. From the way the spell is characterized in the magic item description it seems to fit right in with Fire Ball and Lightning Bolt, the other two attack spells a Staff of Power can create: A d6 of damage for each level of the caster.
Of course that's not a complete spell description, but luckily we find the Wand of Cold further down on page X49 which states that the cone is 60' long and 30' wide at the far end. Now we're almost done with reconstructing the spell, but we should still double-check the details with other sources. So let's look at OD&D and AD&D. We're in for a surprise because OD&D doesn't have Cone Of Cold either! It does have both the Staff of Power and the Wand of Cold but not the spell, just like B/X. AD&D of course has the spell, but it's a tad bit different than what you'd expect from the B/X items:
- The AD&D spell is level 5 and not level 3 as would fit with Fire Ball and Lightning Bolt. That's presumably justified by Cone of Cold having fewer complications regarding area of effect or rebounding?
- The AD&D spell description doesn't give the exact dimensions of the cone, however it does explicitly state that the cone starts from the caster's hands (so the range is 0).
- The AD&D spell does d4+1 damage per level of the caster which guarantees a higher minimum damage but falls short of the possible maximum damage a d6 would provide.
So we'll have to "pick up the pieces" a bit. Personally I find level 5 to be too high, after all that's the same level as Cloudkill which potentially insta-kills creatures of less than 5 hit dice. So let's say it's level 4 instead. Also let's adopt the clear dimensions given for the Wand of Cold and let's make it d6 per level as implied by both B/X magic items. We arrive at the following:
Cone of Cold
This spell creates a cone 60' long and 30' wide at the far end that originates from the magic-user's hands. It does 1-6 (1d6) points of cold damage per level of the caster to all creatures within the cone. A saving throw versus spells will reduce damage by half if successful.
Sounds like a decent B/X spell to me? Also by adding a cold attack spell to the list we can get a little more mileage out of the cleric's Resist Cold, a neat side-effect.
I am sure there will be those who'd argue that the spell is not in fact "missing" at all, it's just that in the B/X world cold attacks only come from White Dragons or magic items. I don't know, I think there should be a spell because wizards have to create those magic items based on something, right?
And if you feel like adding this spell is a bad idea without taking something else away, may I suggest removing Growth of Plants from the magic-user's spell list and giving it to the cleric instead? Seems sensible anyway...