CR 5 Monster: The Mage Slayer [PEACH]

[Gastronomie]

Random idea of an enemy mook adept at crippling the party caster.

The Mage Slayer
Medium/Small Humanoid (any race), any alignment
Hit Points: 85 (10d8+40)
Speed: 40ft/35 ft (Racial + 10ft)
AC: 17 (studded leather armor)
Str 16 (+3) Dex 18 (+4) Con 18 (+4)
Int 14 (+2) Wis 16 (+3) Cha 16 (+3)
Skills: Athletics +6, Acrobatics +7, Perception +6, Stealth +7
Saving Throws: DEX +7, CON +7, WIS +6
Damage Resistance: damage from cantrips
Senses: Passive Perception 16, any racial darkvision
Languages: Any number of languages that the DM feels appropriate
Challenge Rating: 5 (1800 XP)
Limited Magic Resistance. The Slayer has advantage on saving throws against spells and other magical effects activated by a creature within 5 feet. It also has advantage on saving throws made to end the effects of spells and other magical effects that already affect the Slayer.
Swift. The Slayer has advantage on initiative rolls.
Mobile. If the Slayer makes a melee attack against a creature, he does not provoke opportunity attacks from that creature for the rest of the turn, whether he hits or not. The Slayer ignores difficult terrain during movement.

Actions
Multiattack. The Slayer makes three attacks from those described below (it can make multiple attacks of the same type).
Dispelling Blade. Melee Weapon Attack: +7 to hit, reach 5 ft., one target
Hit: 8 (1d8 + 4) slashing damage. Any magical effects affecting the target creature are immediately dispelled.
Disrupting Blade. Melee Weapon Attack: +7 to hit, reach 5 ft., one target
Hit: 8 (1d8 + 4) slashing damage. When this attack damages a creature that is concentrating on a spell, that creature has disadvantage on the saving throw it makes to maintain its concentration.
Entangling Whip. Melee Weapon Attack: +7 to hit, reach 15 ft., one target
Hit: The target is tugged up to 10 feet towards the Slayer.

Reactions
Parry. The Slayer adds +3 to its AC against one attack that would hit.
Mage Slaying. The Slayer makes one melee attack against a creature within attack range which attempted to cast a spell.

Comments and constructive critisism greatly appreciated~!