Cryomancer

You have mastered using cold-based spells to slow your opponents, granting you the following benefits:

• You spellcasting ability score increases by (if you use multiple ability scores for spellcasting, choose one of them to increase).
• Once per turn, when you deal cold damage to a creature with a spell of 1st level or higher, you can reduce that creature's speed by 10 feet until the start of your next turn.
• When you score a critical hit with a spell that deals cold damage to a creature, you can cause the target to be restrained. A creature restrained in this way can use its action to make a Strength check against your spell save DC, ending the condition on a success.