You can read the thoughts of specific creatures for the duration of the spell. You can achieve this effect when you cast the spell or as an action during the duration of the spell. At this point, the subject creature must be within 30 feet of you and be visible to you, and you must focus on it. If the creature’s intelligence is 3 or lower, or does not understand any language, the creature is not affected.
Detect Thoughts 5e
Level: 2nd
Classes: Sorcerer, Wizard, Bard
Casting Time: 1 Action
Range: Self
Components: V, S, M
Duration: Concentration, up to 1 minute
What you first understand is the superficial thinking of the creature, which is generally what it is thinking at the moment. You can use actions to go deeper into the mind of a creature, or you can use actions to shift the goal of mind reading. If you go deeper, the target must make a Wisdom save. When the immunity fails, you learn about his logical reasoning (if any), emotional state, and some big things in his mind (such as worries, love, and hate). When the save succeeds, the spell ends.
In either case, the target will know that you are prying his mind. Unless you divert your attention to another creature, he can use an action to make an intelligence check during his turn and fight your intelligence check; when the creature wins the fight, the spell ends. Questioning the target can guide the target’s thought process, so this spell is particularly effective in interrogation.
You can also use this spell to detect invisible thinking creatures. You can achieve this effect when you cast the spell or as an action during the duration of the spell. At this point, you can search for thoughts within 30 feet. This spell can penetrate most obstacles, but it will still be blocked by 2 feet of stone, 2 inches of metal, or a thin layer of lead material. You cannot detect creatures with intelligence 3 or lower, nor can you detect creatures that do not understand any language.
After detecting a creature in this way, you can read its mind as described above for the duration of the spell. You don’t even need to see the creature, but it must be within 30 feet of it.