Frost Lich

Ice has a certain preserving power. It can slow organic functions completely to a stop, keeping a lifeform in stasis for millennia with only a little magic. The Frost Lich is he who taps into that power on his journey to immortality, keeping himself alive and others immobilized with frost that holds its grip stronger than the grave itself. 

 

Freeze!

At 3rd level, on your turn, whenever you reduce a creature to a number of hit points equal to twice your level using cold damage, it freezes, reducing to 0 hit points. You can freeze a number of creatures per long rest equal to your proficiency bonus. Also at 3rd level, on your turn, you can use an action to raise a number of creatures you froze equal to up to your proficiency bonus as either a zombie or a skeleton (you choose). Undead you raise in this way deal cold damage instead of any other damage type. You can control a number of undead created with this feature equal to your proficiency bonus. You can use this feature a number of times per short or long rest equal to your proficiency bonus.

Frozen Buckler

You can raise the frost around to root yourself in place, forming a formidable defense. At 6th level, as a reaction to being hit with a weapon attack, you can raise your AC by your spellcasting ability modifier, potentially causing the attack to miss. If you do so, your movement speed becomes 0 until the end of your next turn. You can use this feature a number of times per short or long rest equal to your proficiency bonus.

Expendable Minions

At 10th level, as an action during your turn, you can manually explode any amount of undead under your control. Each undead you chose reduces to 0 hit points and dies immediately. Each creature within 10 feet of an undead that explodes in this way must make a constitution saving throw against your spell save DC or take 10 cold damage and have its speed reduced by 10 feet until the end of your next turn on a failed save, taking the cold damage but not having its movement speed reduced on a successful save. In addition, whenever you create an undead with Preserving Frost but already have the maximum amount under control, choose a different undead you control. It drops to 0 hit points and shatters immediately, without expending a use of this feature. You can use this feature a number of times per long rest equal to your proficiency bonus. 

Grasp of the Frost

You can use the numbing power of frost to bring enemies to their inevitable doom and service of you for eternity. At 14th level, whenever you or one of your undead deal cold damage, you can lower the target's speed by 5 feet until the end of your next turn. Once a creature's speed is reduced to 10 feet or lower, it cannot be reduced any more by use of this feature, but the target takes 2d8 cold damage at the start of each of its turns. Once the target's speed becomes 0, it must make a strength saving throw against your spell save DC or the reductions from this feature and from your Icy Resolve last an additional round. If cold damage from this feature reduces a creature to a number of hit points equal to your level, it freezes instantly.