homebrew by u/StoneStrix, modified by Team Brievary
The chronomancer is a 20th-level spellcaster. Its spellcasting ability is Intelligence (save DC 18, +10 to hit with spell attacks). The chronomancer has the following wizard sells prepared:
Cantrips (at will): blade ward, mage hand, ray of frost, prestidigitation
1st level (4 slots): detect magic, expeditious retreat, magic missile, shield
2nd level (3 slots): hold person, misty step
3rd level (3 slots): blink, haste, slow
4th level (3 slots): banishment, dimension door
5th level (3 slot): cone of cold, wall of force
6th level (2 slot): globe of invulnerability
7th level (2 slot): teleport
8th level (1 slot): maze
9th level (1 slot): time stop
Magic Resistance. The chronomancer has advantage on saving throws against spells and other magical effects.
Expose Paradox. The chronomancer chooses one creature it can see within 600 feet of it, revealing to it a paradox in the space-time continuum. The target must make a DC 18 Wisdom saving throw, taking 42 12d6 psychic damage on a failed save, or half as much damage on a successful one. Stretch Time (Recharge 5-6). The chronomancer can take one additional action on its turn.
Rewind. When the chronomancer or another creature makes an attack roll, saving throw, or ability check, it must remake the roll and use the new result.