Deep One Elder

Pressurized — A deep one is immune to damage and other negative effects from changes in water pressure.

Endless — A deep one doesn't age and is immune to spells and other effects that inflict magical aging. Unless killed, a deep one lives forever.

Frightful Presence (aura, emotion, fear, mental) — 60 feet. DC 31 Will.

A creature that fails its save is also Slowed 1 (Slowed 2 on a critical failure).
A creature that first enters the area must attempt a Will save.

Regardless of the result of the saving throw, the creature is temporarily immune to this monster's Frightful Presence for 1 minute.

Critical Success The creature is unaffected by the presence.

Success The creature is Frightened 1.

Failure The creature is Frightened 2.

Critical Failure The creature is Frightened 4.

Mental Mirror — Mental effects that fail against a deep one elder are reflected back onto the source, as Spell Riposte.

Devastation — A deep one elder's claw Strikes ignore the first 10 Hardness of an object. Additionally, on a critical hit, the target must succeed at a DC 34 Fortitude save or be Stunned 2.

Trample — Huge or smaller, foot, DC 31 Reflex

The deep one can Swim up to double its swim Speed instead of Striding.
The monster Strides up to double its Speed and can move through the spaces of creatures of the listed size, Trampling each creature whose space it enters. The monster can attempt to Trample the same creature only once in a single use of Trample. The monster deals the damage of the listed Strike, but trampled creatures can attempt a basic Reflex save at the listed DC (no damage on a critical success, half damage on a success, double damage on a critical failure).

Watery Void (concentrate, manipulate, occult, void, water) — The deep one elder makes an endless void of water appear in a 20-foot burst within 60 feet, dragging creatures down into its whirlpool. If cast underwater, the watery void fills a 60-foot-tall cylinder with a 20-foot radius. Creatures in the area when the void appears and creatures that end their turn in the area take 3d8 bludgeoning damage and 3d8 void damage and must attempt a DC 31 Reflex save. The void remains until the end of the deep one elder's next turn. The deep one elder can Sustain the void to extend the duration by 1 round, up to a total of 4 rounds, and can move the void up to 15 feet. Once the effect ends, the elder can't use Watery Void again for 1d4 rounds.

Critical Success The creature is unaffected.

Success The creature takes half damage and a –5-foot circumstance penalty to their Speeds while in the void.

Failure The creature takes full damage and a –10-foot circumstance penalty to their Speeds while in the void.

Critical Success The creature takes double damage, is knocked Prone, and takes a –10-foot circumstance penalty to their Speeds while in the void.

Improved Knockdown —