True Vision

Choose any number of creatures in sight. They will see true vision of the worst future possible (in their perspective).
This is affected by your alignment and personality. What players see is up to DM's digression.  The vision doesn't have to be future, it can be simply possibility for future.
For example
Lawful Good may see destruction of his home city as result of war.
Chaotic Evil may see him being captured and locked up forever.
Antagonist may see his plans being foiled by adventurers.

The vision will be of the worst possible future. The creature can feel with all of their senses and in addition they can feel emotions and pain, if this makes the vision feel worse.
All creatures must make WIS saving throw (spellcasters dc or dc 15, whichever is higher). On failed save creature takes 3d10 psychic damage and half as much on successful save.

Vision only lasts seconds, but it can feel much longer for creatures affected. Targets cannot remember anything specific from their vision (and DM doesn't have to describe anything specifically), but targets understand it was horrible vision and can have lingering sense of pain or the emotions they felt.

*When Heart of Algrem uses True Vision it shows possible future that mishandling it could cause