Cassiok Shadowdusk

Cassiok has advantage on saving throws against spells and other magical effects.

Cassiok carries a staff of power that grants him a +2 bonus to Armor Class, spell attack rolls, and saving throws. His insectoid physiology prevents him from making melee attacks with the staff. If reduced to 20 hit points or fewer, Cassiok uses his next action to break his staff in a retributive strike.

Cassiok is an 18th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 17, +9 to hit with spell attacks). Cassiok can cast disguise self and invisibility at will and has the following wizard spells prepared:

• At will: disguise self, invisibility.

• Cantrips (at will): fire bolt, light, mage hand, prestidigitation, shocking grasp
• 1st level (4 slots): detect magic, identify, mage armor*, magic missile
• 2nd level (3 slots): detect thoughts, mirror image, misty step
• 3rd level (3 slots): counterspell, fly, lightning bolt
• 4th level (3 slots): banishment, fire shield, stoneskin*
• 5th level (3 slots): cone of cold, scrying, wall of force
• 6th level (1 slots): globe of invulnerability
• 7th level (1 slots): teleport
• 8th level (1 slots): mind blank*
• 9th level (1 slots): time stop

*Cassiok casts these spells on itself before combat.

Any spellcaster that can cast the find familiar spell (such as an archmage or mage) is likely to have a familiar. The familiar can be one of the creatures described in the spell (see the Player's Handbook) or some other Tiny monster, such as a crawling claw, imp, pseudodragon, or quasit.