Aurangal, Mind Flayer Horizon Ranger

Magic Resistance. The mind flayer has advantage on saving throws against spells and other magical effects.

Land's Stride. Moving through nonmagical difficult terrain costs the mind flayer no extra movement. The mind flayer can also pass through nonmagical plants without being slowed by them and without taking damage from them if they have thorns, spines, or a similar hazard.

Hide in Plain Sight. The mind flayer can spend 1 minute creating camouflage for itself. The mind flayer must have access to fresh mud, dirt, plants, soot, and other naturally occurring materials with which to create its camouflage.

Once the mind flayer is camouflaged in this way, it can try to hide by pressing itself up against a solid surface, such as a tree or wall, that is at least as tall and wide as the mind flayer is. The mind flayer gains a +10 bonus to Dexterity (Stealth) checks as long as it remains there without moving or taking actions. Once the mind flayer moves or takes an action or a reaction, it must camouflage itself again to gain this benefit.

Planar Warrior. As a bonus action, the mind flayer can choose one creature it can see within 30 feet of itaelf. The next time the mind flayer hits that creature on this turn with a weapon attack, all damage dealt by the attack becomes force damage, and the creature takes an extra 1d8 force damage from the attack.

Favored Enemies. The mind flayer has advantage on Wisdom (Survival) checks to track humans, tieflings, dragonborn and gith, as well as on Intelligence checks to recall information about them.

Favored Terrain. The mind flayer is particularly familiar with mountains, swamps, and the underdark and is adept at traveling and surviving in such regions. When the mind flayer makes an Intelligence or Wisdom check related to its favored terrain, its proficiency bonus is doubled if it are using a skill that it's proficient in.

While traveling for an hour or more in its favored terrain, the mind flayer gain the following benefits:

Difficult terrain doesn’t slow its group’s travel.
Its group can’t become lost except by magical means.
Even when the mind flayer is engaged in another activity while traveling (such as foraging, navigating, or tracking), it remains alert to danger.
If the mind flayer is traveling alone, it can move stealthily at a normal pace.
When the mind flayer forages, it finds twice as much food as it normally would.
While tracking other creatures, the mind flayer also learns their exact number, their sizes, and how long ago they passed through the area.

Innate Spellcasting (Psionics). The mind flayer’s innate spellcasting ability is Intelligence (spell save DC 15). It can innately cast the following spells, requiring no components:

At will: detect thoughts, levitate

1/day each: dominate monster, plane shift (self only)

Spellcasting. The mind flayer is a 10th-level spellcaster. Its spellcasting ability is wisdom (spell save DC 16, +8 to hit with spell attacks). The mind flayer has the following ranger spells known:

1st level(4 slots): detect magic, [Tooltip Not Found], goodberry, hunter's mark, protection from evil and good

2nd level(3 slots): misty step, pass without trace

3rd level(3 slots): haste, nondetection

Primeval Awareness. The mind flayer can use its action and expend one ranger spell slot to focus its awareness on the region around itself. For 1 minute per level of the spell slot the mind flayer expends, it can sense whether the following types of creatures are present within 1 mile of itself (or within up to 6 miles of itself if it is in its favored terrain): aberrations other than mind flayers, celestials, dragons, elementals, fey, fiends, and undead. This feature doesn’t reveal the creatures’ location or number.

Detect Portal. As an action, the mind flayer can detect the distance and direction to the closest planar portal within 1 mile of it.

Once the mind flayer uses this feature, it can't use it again until it finishes a short or long rest.

Multiattack. The mind flayer makes two attacks.

Longbow. Ranged Weapon Attack: + 7 to hit, range 150/600 ft., 1 target. Hit: 7 (1d8 + 3) piercing damage. 

Tentacles. Melee Weapon Attack: + 7 to hit, reach 5 ft., 1 target. Hit: 14 (2d10 + 3) psychic damage. If the target is Medium or smaller, it is grappled (escape DC 15) and must succeed on a DC 15 Intelligence saving throw or be stunned until this grapple ends.

Extract Brain. Melee Weapon Attack: + 7 to hit, reach 5 ft., 1 target that is incapacitaed and grappled by the mind flayer. Hit: 55 (10d10) piercing damage. If this damage reduces the target to 0 hit points, the mind flayer kills the target by extracting and devouring its brain.

Mind Blast (Recharge 5-6). The mind flayer magically emits psychic energy in a 60-foot cone. Each creature in that area must succeed on a DC 15 Intelligence saving throw or take 21 (4d8 + 3) psychic damage and be stunned for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.