Anguiliian

The Anguiliian is a creature that appears like a Frost Salamander, and is meant to be some kind of spear wielding avenging warrior of the Shark Father Sekolah.
==Gameplay==
This is a summoned creature that may appear only in the Underwater City. It is actually summoned by script, not some kind of conjuring from a specific spell casting Sahuagin.
The triggered events that lead to this creature's appearance relate to whether the party is viewed as an enemy of the King Ixilthetocal and the entire city populace is made hostile to the PC. Once a global called "hatePC's" is set, then it's too late, and the events will initiate.
For example, right from the very first exchange of dialogue with Royal High Priestess Senityili the party can refuse to cooperate even a little bit with the sahuagin. This will make the entire populace hostile to the party (shuttering The prophecy of Sekolah quest elements). If that occurs, then the script will trigger that can summon the Anguillan and other creatures to help defend the city.
The summoning of the Anguiliian is also accompanied by various summoned Undead (such as several Skeleton Warrior creatures, and holy retribution spell casts on the party (ostensibly by Sekolah), including Flame Strike, Command, and Rigid Thinking. 
These creatures appear alongside other sahuagin defenders in the center part of the map, and there are two scripted summoning events.
As interesting as this event may sound, these summoned creatures really aren't a threat of any consequence to a party at this stage of the saga. The retribution of Sekola is mostly for visual enhancement and a bit of flavor to the fact that the party has decided to take on the whole populace and forego any role-playing opportunities in this area. Every sahuagin will be an enemy on this map from now on. Let the slaughter commence.
==Gallery==
UW City Hostile.png|Party has made the city hostile - a Anguiliian and Skeleton Warrior rise forth to assist the sahuagin defenders.
==Mod content==
The Sword Coast Stratagems mod revises the creature by assigning spear and two-handed weapon style proficiencies (which the base game did not do).
It also provides immunities to entangle, web and few other effects that are to reflect that these creatures are large and can't be restricted by that sort of stuff.
The original Tactics Mod which can still work with the non-EE original classic game made the challenge level much greater in the City of Caverns. That mod increases the difficulty factor to a real threat.