SRD 5.2.1 · Senses
A magically transformed creature is seen within Truesight range. Does discerning its true form itself end the transformation?
No; it reveals the true form without a general instruction to end the effect.
The entry says the observer discerns the true form. It does not say the transformation is dispelled or the target changes back. Use the information when describing what the observer perceives, then consult the transformation’s actual rules for ending it. The same distinction applies between seeing through a visual illusion and ending that illusion for everyone.
Truesight does not state that every lie, hidden intention or nonvisual deception is exposed. Tie the benefit to one of its listed visual capabilities and the actual range.
Which listed visual benefit applies, and what does it reveal without changing the target?
If you have Truesight, your vision is enhanced within a specified range. Within that range, your vision pierces through the following: Darkness. You can see in normal and magical Darkness. Invisibility. You see creatures and objects that have the Invisible condition. Visual Illusions. Visual illusions appear transparent to you, and you automatically succeed on saving throws against them. Transformations. You discern the true form of any creature or object you see that has been transformed by magic. Ethereal Plane. You see into the Ethereal Plane.
Source: SRD 5.2.1, 190. Online guide.
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