When a Tome of Power is active, the Hellstaff's firing rate slows down, and it launches powerful projectiles which deal 10-80 damage and summon "clouds" of red rain above the area of impact, at the cost of five runes per shot. Every tick, the summoned cloud of rain has a ~90.2% chance to spawn a raindrop within a 64-unit radius, and each raindrop does 5-40 damage. Only 2 clouds can be active at once; summoning a third destroys the oldest one. Larger foes, such as an Iron Lich, are likely to get hit by more droplets than smaller foes, hence causing more damage. However, boss foes (the Maulotaur and D'Sparil) have a partial immunity to this attack, reducing the damage each drop does to them by 80%.