The Warden is an upcoming hostile mob in the 1.17 - Caves and Cliffs update.

The Warden will be the first blind mob to be added to Minecraft. Instead of following the player normally, it uses the sculk-like sensors on its head to detect vibrations.

A good defense to use in order to avoid fighting the Warden is to sneak or throw projectiles such as snowballs or arrows to distract it, which was shown during the Minecraft Live 2020 event. It was shown in the reveal that the Warden will be attracted to projectiles that produce a sound. However, fighting the Warden is not recommended, as it does a lot of damage. Mojang developers also stated that this mob is not meant to be fought, but rather is meant to scare players.

The Warden seems like it gets faster when attacked, and it deals so much damage that it can kill a player wearing full netherite armor in two hits (any weaker armor or no armor will result in the player being killed in 1 hit).

The Warden won't hear the player if the they sneak past it, but if the player attacks it enough, it will lock onto them and won't get distracted by other noises. At this point, it will begin charging at the player significantly faster than before.

If a player gets near to it or tries to attack it with poison, wither, or other similar status effects, then the warden will still attack the player.

Its heartbeat is audible as well as visible, and the more it is attacked, the stronger it gets, and the stronger it gets, the more its soul-filled heart flashes.

More facts here: https://minecraft-archive.fandom.com/wiki/Warden