Hayate Yagami, Mistress of the Night SkyAbilitiesNG Human Archivist 20
Feats: Cold Spell Specialisation, Elder Giant Magic, Energy Substitution (cold), Enlarge Spell, Frozen Magic, Iron Will
B, Leadership, Piercing Cold, Primitive Caster, Reserves of Strength, Snowcasting, Southern Magician, Versatile Spellcaster
Flaws: Meager Fortitude, Shaky
Skills: Use Magic Device
Equipment: Ankh of ascension, Horizon goggles, Ioun Stone (orange prism), Otyugh hole, Schwertkreuz (Runestaff of frost/Rod of elemental might (water)
CM), Ring of arming, Wings of flying
Diabolic Emission: Wings of flurry or
Circle of deathAtem des Eises: Otiluke's freezing sphereHraesvelgr: Energy substituted (cold)
meteor swarm (has up to 2,280ft range)
Misteltein: Flesh to stoneRagnarok:Hayate takes longer to cast her spells than other casters, and needs both a chanted aria and to have the Book of the Night Sky at hand - this is represented by Snowcasting (which requires a move action to gather snow) and Elder Giant Magic, and Primitive Caster to add verbal and
material focus components. This also represents her immense power.
(her CL can get as high as 29).
For spells which appear on the wu jen's Water list she can use her Rod of Elemental Might to increase the CL by an additional +2 if she succeeds on a DC 26 Use Magic Device check. Her Ankh of Ascension can boost it by +4 3/day. Reserves of Strength can increase it by +3 in exchange for stunning, while also
removing damage caps. So her maximum CL is 38.
Her lack of low-level magic is represented by Versatile Spellcaster (combine two spell slots into one a level higher) - the spontaneous casting requirement is handled by her runestaff.
As a "mage knight", Hayate has the Southern Magician feat to represent her combination of Belkan and Midchildian magic. This also qualifies her for the Attain Familiar and Improved Familiar feats, if you want Zafira for some reason. (Zafira: *sobs silently*)
Reinforce Zwei (cohort)Jermlaine (ritual of alignment) Cleric (Knowledge, Winter) 12/Fiend of Possession 6
NG Tiny Outsider (evil)
Feats: Cold Focus, Educated, Greater Cold Focus, Knowledge Devotion, Otherworldly
Spells: Enlarge person(?) - needs something that works on Outsiders
While Hayate has the Frostburn feats which make cold spells stronger, Rein has the ones which make them harder to avoid. Hayate is "a total clutz" without Rein. She is also not as useful possessing characters who do not specialise in cold magic, though they should still find the +5 attack/damage from Knowledge Devotion welcome.
If Rein having the ability to speak to rats weirds you out, apply the dragonborn template. This also lets her pick up a fly speed.