Unspeakable Word

Necrotic Spell, Tier 6, 2 Actions, Single Target

Reach: 8. Damage: d66 (with advantage, ignoring armor, does not miss or crit) on a failed INT save. Target rolls with disadvantage if Bloodied or Frightened. On a success, you both take half of this damage instead. Upcast: +1 DC, +10 damage.

D66 with advantage. Roll 3d6 and drop the lowest die. The leftmost die is the tens place, and the second is the ones (e.g., 2, 3, and 4 deals 34 damage).

From Core Rules