The Trial Spawner is a special type of mob generator found in the Trial Chambers announced for Minecraft 1.21.
Trial Spawners resemble monster generators. Although they both have skulls at the corners, Trial Spawners also have skulls on their sides. The top four corners evoke lights, similar to skull eyes, emitting a soft orange glow.
Trial Spawners cannot be obtained in Survival mode. They are highly resistant to explosions and have the same strength as Reinforced Abyssal Slate.
A Trial Spawner generates a set number of monsters, based on the number of surrounding players. Once these mobs have been defeated, it delivers a reward for each player and enters the recovery phase.
During a demonstration at the Minecraft Live event, the spawner was shown to produce emeralds and diamonds. However, these items may only be indicators and may not appear as rewards in the final version.
Like a classic monster generator, a Trial Spawner activates when a player approaches it.
When activated, it releases flame-like particles into the air. It also projects flame-like particles around the monsters it generates, depending on the number of players in the vicinity.
It has not yet been established whether the level of lighting around a Trial Spawner influences the way it causes mobs to appear.
Blocks placed on the ground near a Trial Spawner provide information on the type of monster it generates when activated.
During the Minecraft Live demo, blocks of compacted ice on the ground surrounding a Trial Spawner signaled the generation of wanderers. Breezes and slimes were also shown during this demonstration. Although the blocks associated with their respective Trial Spawner were not specified, slimes could be seen near a Trial Spawner made of foam blocks, and breezes near a Trial Spawner made of polished tuff.