Astral Barrier (5e Spell)
From D&D Wiki
|Casting time:||1 reaction, which you take when you are hit by an attack|
As you notice a particularly painful attack headed your way, you call upon the power of the stars to try and blunt the damage. Make a DC(15)Constitution saving throw, decreasing the incoming damage by 1d6 on a success.
At Higher Levels. The damage reduction increases by 1d6 when you reach 7th level (2d6), 13th level (3d6), and 17th level (4d6).