When you hit a Fiend or an Undead with this magic weapon, that creature takes an extra 2d6 Radiant damage. If the target has 25 Hit Points or fewer after taking this damage, it must succeed on a DC 15 Wisdom saving throw or be destroyed. On a successful save, the creature has the Frightened condition until the end of your next turn.
Light. While you hold this weapon, it sheds Bright Light in a 20-foot radius and Dim Light for an additional 20 feet.
+2d6 radiant vs fiends/undead; ≤25 HP undead must save or be destroyed.
RollQuest ships the D&D 2024 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.