Vorka the Ice Mage

Special Equipment. Vorka has a Staff of Frost, a Frostbrand Shortsword, and a Robe of the Archmagi. She is attuned to all three of these magic items.

Relentless Endurance (1/day). When Vorka is reduced to 0 hit points but not killed outright she goes to 1 hit point instead. 

Magic Resistance. Vorka has advantage on saving throws against spells and other magical effects.

Divine Favor. If Vorka fails a saving throw or misses with an attack roll, she can roll 2d4 and add it to the total.

Dark One's Blessing. When Vorka reduces a hostile creature to 0 hit points, she gains 6 temporary hit points.

Spellcasting. Vorka is a 5th-level multiclass spellcaster. Her spellcasting ability is Charisma (spell save DC 18, +10 to hit with spell attacks). Vorka has the following sorcerer and warlock spells prepared:

Cantrips (at will): Chill Touch, Mage Hand, Ray of Frost, Blade Ward, Frostbite

1st level (6 slots): Armor of Agathys, Command, Ice Knife, Chaos Bolt, Bane 

2nd level (2 slots): Dragon's Breath, Snilloc's Snowball Swarm

Frostbrand Shortsword. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 8 (1d6 + 4) piercing damage plus 4 (1d6) cold damage. This attack deals an extra 4 (1d6) piercing damage if Vorka had advantage on the attack roll or there is an ally of hers within 5 feet of the target.

Staff of Frost. Vorka expends charges from her Staff of Frost to cast one of the following spells (DC 18): Cone of Cold (5 charges), Fog Cloud (1 charge), Ice Storm (4 charges) or Wall of Ice  (4 charges).

Ray of Frost. Ranged Spell Attack: +10 to hit, range 60ft., one target. Hit: 10 (2d8) cold damage, and its speed is reduced by 10 feet until the start of her next turn.