Half orc
15 point buy
I want him able to do melee but be all icy cold spells
I have thought barb/oracle of the waves
or battle cleric with appropriate domains
We can use the core and theultimate pf books
Help?
In reign of winter player guide there is a winter oracle.
A half orc, with a falcion and the right revelations would make a very decent melee/caster... the winter oracle has some cool cold stuff.
A coldspell based magus would also do a decent melee/cold caster.
If you want nasty, look at Oracle of Metal...and just find some cold spells, the revelations are stunningly good.
A close second is Oracle of Nature, which could also fit into the cold theme.
A half orc barb/oracle of nature or metal/ rage prophet would be particularly effective as well.
With only 15 point buy, a nature oracle with the whispers of nature revelation (cha to AC instead of dex) is very helpful, especially when limited to medium armor.
A barbarian (armored hulk)/oracle of metal/Rage prophet is a scary thing to look at, but will take some time (12th level ish) before the build comes into its own.
Personally I think the magus will fit your idea to a "T" you can spam Ray of frost even when out of spells (keeping with the idea of all attacks doing frost.) Personally I would go Hexcrafter and bladebound, See if the gm is ok with it being a blue frosted blade instead of a black blade (have it always hungering for warmth) and hexcrafter...well because hexcrafters are cool. Slumber could be flavored by saying you lower the body temperature to make them fall asleep and there are some cold hexes.
For some tips on how to effectively use cold spells as a magus, you might want to check out STR Ranger's and Mathwei apNall's guide called "Magus Hexcrafter Guide: The Complete Guide For Dealing With The Devil". It can be found in the guides section, or :here
The second build in that guide (labeled "the defiler") details some ways to maximize the effectiveness of a couple low level cold spells in order to cause various no save status effects at once that can practically cripple an opponent. A lot of the other things in that build you can ignored (the stuff about using white haired witch's natural attack is actually outdated, and it no longer works under the current rules; it also was a rather extreme power build). The general idea was to use Rimed spell (with a few key traits to keep it from raising the spell level when altering two key spells) in order to entangle an opponent while applying either fatigued (from frostbite) or staggered (from Frigid Touch) without any save.
Because what can be more satisfying for a cold based villian than to see than to see his enemies fall to their knees before the ever encroaching march of a never ending winter? Add on hexcrafter on top of that and you can strike down anything that dares stand before you. Mwh--- Wait....oh, forgot to take my meds again.
Anyway, for the point buy: If you are not too adverse to dump stats, you can get a somewhat decent set of scores like these:
STR: 16 (14+2) DEX: 14 CON: 14 INT: 14 WIS: 9 CHA: 7
Mix up the mental scores however you like depending on what class you pick. I dumped CHA here (since it seems almost customary on these boards), but Wisdom is usually not too troublesome to dump low since most of the casting classes have good will saves. You could also drop DEX and CON down a hair each so that you only have to make only one dump stat mentally (and it would only need to be at a 9 at that). I'd advise keeping the 16 in strength though, since it is usually the minimum for a strength based melee build. If you want to go with dervish dance...well, I have little advice for you. I try to stay away from that...just switch the dex and strength advice. 13 STR is still a general prerequisite even then, since you need that much for power attack.