Scion of Abraxas. The xacarba has advantage on attack rolls against creatures with the  Spellcasting or Pact Magic abilities. It also has advantage on saving throws against spells and magical effects.

Multiattack. The xacarba uses Replicate Spell and makes one Bite, Tail, or Constrict attack.

Spellbane Bite. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 16 (2d10 + 5) piercing damage, and the target needs to make a DC 17 Constitution saving throw. On a failed save, a creature takes 24 (7d6) poison damage and is poisoned for 1 minute. On a successful save, a creature takes half damage and isn't poisoned. While poisoned in this way, a creature cannot cast spells, maintain concentration on an active spell, benefit from another creature's spell, or activate magical items. A poisoned creature can reroll its saving throw at the end of each of your turns, ending the effect on a success.

Tail. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 14 (2d8 + 5) bludgeoning damage, and the xacarba can choose to grapple the target (escape DC 17). Until this grapple ends, the creature is restrained, and the xacarba can't grapple another target.

Constrict. One creature that is currently grappled by the xacarba must make a DC 17 Strength saving throw. On a failed save, the creature takes 31 (4d12 + 5) bludgeoning damage. On a successful save, it takes half damage.

Replicate Spell. The xacarba casts one spell from any spell list that is of 6th-level or lower, using Intelligence as its spellcasting ability (spell save DC 17, +9 to hit with spell attacks).

Spell Reflection (Recharge 5-6). If the xacarba makes a successful saving throw against a spell, or a spell attack misses it, the xacarba can choose another creature (including the spellcaster) it can see within 120 feet of it. The spell targets the chosen creature instead of the xacarba. If the spell forced a saving throw, the chosen creature makes its own save. If the spell was an attack, the attack roll is rerolled against the chosen creature.