Guardian Golem

Type	Light pet
Use time	20 (Very fast)
Tooltip	Summons a toy golem to light your way; 'Power cells not included.'
Rarity
Sell	5
Research	1 required
Buff	Toy Golem
Buff tooltip	Got myself a crying, talking, sleeping, walking, living idol!
Use	https://terraria.wiki.gg/wiki/File:Item_2.wav

Desktop/Console/Mobile-Only Content: This information applies only to the Desktop, Console, and Mobile versions of Terraria.

Master Mode-Only Content: This information applies only to Master Mode and Master Mode worlds.

The Guardian Golem is a Master Mode-exclusive light pet dropped by the Golem with a 25*1/4 (25%) chance. Upon being used or equipped, it summons a Toy Golem light pet.

Trivia

The phrase in the Guardian Golem's tooltip, "Power cells not included", is a nod to how most battery-powered toys in commercials and advertisements state a similar warning for "batteries not included", and alludes to how Golem is summoned with Lihzahrd Power Cells.
The buff's tooltip is a reference to the song Living Doll written by Lionel Bart for Cliff Richard and The Shadows (then still known as "the Drifters") in 1959. The original lyrics were: "Got myself a cryin', talkin', sleepin', walkin', livin' doll". The tooltip simply replaces "doll" with "idol", as Golem is the Lihzahrdian Idol.
When summoned, the pet will always attempt to position itself in front of the player. This is likely because it is meant to act as a guardian, hence the name of the item.