Multiattack. The diviner makes three Arcane Burst attacks.
Arcane Burst. Melee or Ranged Spell Attack: +7 to hit, reach 5 ft. or range 120 ft., one target. Hit: 20 (3d10 + 4) radiant damage.
Overwhelming Revelation (Recharge 5–6). The diviner magically creates a burst of illumination in a 10-foot-radius sphere centered on a point within 120 feet of it. Each creature in that area must make a DC 15 Wisdom saving throw. On a failed save, a creature takes 45 (10d8) psychic damage and is stunned until the end of the diviner's next turn. On a successful save, the creature takes half as much damage and isn't stunned.
Spellcasting. The diviner casts one of the following spells, using Intelligence as the spellcasting ability (spell save DC 15):
At will: mage hand, message, prestidigitationPortent (3/Day). When the diviner or a creature it can see makes an attack roll, a saving throw, or an ability check, the diviner rolls a d20 and chooses whether to use that roll in place of the d20 rolled for the attack roll, saving throw, or ability check.