Kazrith
Medium elemental magical beast (demon, water)
Level 20 Lurker XP 2800

Initiative +22        Senses Perception +19; tremorsense 20
HP 146; Bloodied 73
AC 34; Fortitude 32, Reflex 34, Will 30
Immune acid; Resist 20 variable (2/encounter)
Speed 6, burrow 6 (tunneling), swim 8

(⚔) Bite (standard, recharge ⚄⚅) ✦ Acid

+25 vs AC; 2d6+4 damage, and ongoing 5 acid damage (save ends).

ᗕ Acidic Retreat (standard, recharge ⚄⚅) ✦ Acid

Close burst 2; +23 vs Reflex; 1d6+4 damage, and ongoing 10 acid damage (save ends). Effect: The kazrith burrows its speed.

Acidic Seepage (usable only while bloodied) ✦ Acid

The kazrith gains a +4 bonus to its burrow speed, and at the start of its turn creatures adjacent to it take 10 acid damage.

Slippery

A kazrith makes saving throws against immobilized, restrained, and slowed conditions at the start of its turn as well as at the end of its turn.

Alignment Chaotic evil        Languages Abyssal, Primordial
Skills Stealth +23
Str 22 (+16)      Dex 26 (+18)      Wis 19 (+14)
Con 20 (+15)      Int 14 (+12)      Cha 12 (+11)

Published in Monster Manual 2, page(s) 55.