Detect Motions

For the duration, you can sense the motions of certain creatures. When you cast the spell and as your action on each turn until the spell ends, you can focus your mind on any one creature that you can see within 30 feet of you. If the creature you choose has a Dexterity of 3 or lower or cannot move, the creature is unaffected.

You initially feel the surface motions of the creature—what movements it is most casually performing. As an action, you can either shift your attention to another creature's motions or attempt to probe deeper into the same creature's body. If you probe deeper, the target must make a Constitution saving throw. If it fails, you gain insight into its more fine movements, its physical feelings, and something that their body is most focusing on in that moment. If it succeeds, the spell ends. Either way, the target knows that you are probing into its body, and unless you shift your attention to another creature's motions, the creature can use its action on its turn to make a Dexterity check contested by your Intelligence check; if it succeeds, the spell ends.

Movements obviously directed at the target creature naturally shape the course of its motions, so this spell is particularly effective as part of stealth recon.

You can also use this spell to detect the presence of moving creatures you can't see. When you cast the spell or as your action during the duration, you can search for motions within 30 feet of you. The spell can penetrate barriers, but 2 feet of rock, 2 inches of any metal other than lead, or a thin sheet of lead blocks you. You can't detect a creature with a Dexterity of 3 or lower or one that cannot move.

Once you detect the presence of a creature in this way, you can feel its motions for the rest of the duration as described above, even if you can't see it, but it must still be within range.