Diem (Japanese: ) is a skill used by Rune in Phantasy Star IV: The End of the Millennium. It defeats a single enemy instantly, if successful. Rune's mental stat, the enemy's mental stat, and the enemy's bio sensitivity affect Diem's success rate. Enemies immune to bio effects, particularly Machines, Zombies, Dimensional Demons, Ghosts, and most bosses, are immune to Diem.
Diem can be combined with Hahn's SaVol technique in any order to do a Holocaust combo.
Rune learns Diem at level 24.