Spellcasting. The mage is a 9th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 14, +6 to hit with spell attacks). The mage has the following wizard spells prepared:

Cantrips (at will): Fire Bolt, Light, Mage Hand, Prestidigitation

1st level (4 slots): Thunderwave, Mage Armor, Magic Missile, Shield

2nd level (3 slots): Enlarge/Reduce, Hold Person

3rd level (3 slots): Counterspell, Fireball, Haste

4th level (3 slots): Polymorph, Wall of Fire

5th level (1 slot): Cloudkill

Eye of Chaos. When Okaun dies, Zndrsplt creates a unbreakable barrier for one round an cries over his lost friend. After this round Zndrsplt becomes enraged and casts flying and Mage Armor on himself and regains all expanded skill slots. He gains the highest initiative for this fight and can cast an additional spell per round as a Bonus Action for the rest of the encounter.

Command. As an Action on his turn Zndrsplt can command Okaun to attack a enemy in his sight. 

Dagger. Melee or Ranged Weapon Attack: +5 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 4 (1d4 + 2) piercing damage.

Staff of Wisdom: Ranged Weapon Attack: +5 to hit, reach 5o ft., one target. Hit 1d10+3 psychic damage. The person who holds the Staff of Wisdom gains Truesight. The modifier for attacks with this weapon is Wisdom.

Dodge Ball. When Zndrsplt is attacked he can throw a saving throw on Dexterity to dodge the attack and jump from Okaun´s left shoulder to his right.

Protect the Big. Once per fight Zndrsplt can react to a AoE Spell that is about to hit Okaun and himself by doing so, he can negate all the damage that Okaun would take.