Guardgoyle (CR 2)

Small Construct
Alignment: Always neutral
Initiative: +4 (Dex)
Languages: Cannot speak

AC: 20 (+1 size, +4 Dex, +5 natural), touch 15, flat-footed 16
Hit Dice: 2d10+10 (21 hp); DR: 5/adamantine or bludgeoning
Fort +0, Ref +4, Will +0
Speed: 20 ft., fly 50 ft. (good)
Space: 5 ft./5 ft.
Base Attack +1; Grapple -1
Attack: Bite +6 melee
Full Attack: Bite +6 melee and 2 claws +4 melee
Damage: Bite 1d4+2 plus poison; 2 claws 1d3+1
Special Attacks/Actions: Poison, shriek
Abilities: Str 15, Dex 19, Con -, Int 6, Wis 11, Cha 10
Special Qualities: Alarm, construct traits
Feats: Multiattack; Weapon Finesse
Skills: Hide +10 and Move Silently +7
Advancement: 3-4 HD (Small); 5-6 HD (Medium)
Climate/Terrain: Any
Organization: Solitary or gang (2-4)
Treasure/Possessions: None

Source: City of Splendors: Waterdeep

Construct Traits: A guardgoyle has immunity to poison, magic sleep effects, paralysis, stunning, disease; death effects, necromancy effects, mind-affecting spells and abilities (charms, compulsions, phantasm, patterns, and morale effects), and any effect that requires a Fortitude save unless it also works on objects or is harmless. It is not subject to critical hits, nonlethal damage, ability damage, ability drain, fatigue, exhaustion, or energy drain. It cannot heal damage, but it can be repaired.

It has darkvision out to 60 feet and low-light vision.

Poison (Ex): Injury or contact, Fortitude DC 11, initial and secondary damage 1d4 Con. The save DC is Charisma-based. A guardgoyle stores enough poison in its fangs for two poisonous bites. After that, its poison must be replenished. Other types of poison are possible.

Shriek (Su): A guardgoyle can emit an ear-piercing shriek in a cone-shaped burst with a range of 30 feet. Any creature within the area is deafened for 1d2 rounds and takes 2d6 points of sonic damage. A DC 11 Fortitude save negates the deafening effect and reduces the damage by half. The save DC is Charisma-based.

Alarm (Sp): If an item guarded by a guardgoyle is disturbed in any way, the person who gave the creature its charge receives a mental alarm from the guardgoyle. The range of this ability is 1 mile; if the guardgoyle's master is farther away, he is not warned. The master notes a single mental "ping" that awakens him from normal sleep but does not otherwise disturb concentration. A silence spell has no effect on a mental alarm.

Guardgoyles are straightforward combatants, shrieking in warning and then attacking with their natural weapons. In the presence of spellcasters they cannot attack directly, they continue to use their shriek ability to disrupt spellcasting.