Astral Flan (Epic)

Elemental Absorption. Any force damage the flan would take instead restores that much HP to the flan.

Spellcasting. The flan is a 17th-level Sorcerer. Its spellcasting ability is Charisma (spell save DC 21, +13 to hit with spell attacks). The flan can use following Sorcerer spells:

• At will: Counterspell, Eldritch Blast, Magic Missile, Shield
• 3/day each: Confusion, Magic Missile (Lv. 4), Steel Wind Strike
• 1/day each: Blade of Disaster, Dark Star, Disintegrate, Mordenkainen's Sword

Flan Fury. The flan casts an at-will spell, then makes 2 slap attacks. Otherwise it simply attempts to cause the most amount of damage possible using one of its most powerful spells as its Action. 

Slap. Melee Weapon Attack: +12 to hit, reach 10 ft., 1 target. Hit: 20 (4d6 + 6) bludgeoning damage plus 9 (2d8) force damage. 

Fast Casting. The flan can cast any of its at will spells once. 

Auto-Reflect. When the flan is affected by a harmful spell, it casts Reflect upon itself (requiring no components); a 7th-level enchantment that will reflect the next spell attempting to harm the flan back at the caster using the caster's own DC/spell attack bonus. A spell being reflected this way is not being cast and therefore cannot be countered once reflected. 

Defensive Spells. Counterspell, Shield.