Hiding is a part of the class skill set of a Thief and a Hunter.
You may hide only if nobody is attacking you from a distance that depends on your skill. You may also hide from your enemy behind an object.

Skill’s efficiency

There is a huge bonus for Thieves.

While hidden you activate the “Assassination” mode.
The current mode allows you to hit once with bigger damage while hidden, your character will drop the weapon, and a “Surprise Attack” message pops up.
The rest of the classes don’t have this unique mode to Hidden.

Detection while being Hidden

You can reveal a hidden character with the Detect Hidden skill, Reveal spell, and explosive potions. A character can be protected from Detect Hidden only with the help of clothes that increase your hiding skill. Magic protection with Blackrock +6 will make you safe from the Reveal spell, although it stops protecting you at the distance of 1-2 tiles from the spell.
There is no way to avoid being noticed after the explosive spells, so the best recommendation would be to escape them.

Most monsters have an ability to detect hidden, so be alert when passing them. Besides, there are traps on the ground in the dungeons that inflict damage and stop your Stealth mode.

Ways of leveling your Hiding

This is a useskill. This means that you have to assign a button to it in the settings for prompt use of the Hiding skill.
Paperdoll – Options – Uo Icon

In case you have any questions you can ask them on our Discord channel:

Here is a detailed video of how the skill is used: