Phantasmal Killer

Level 4 Illusion spell available to Wizards. One Wisdom save and the target is rooted in place, attacks with Disadvantage, and takes 4d10 Psychic at the end of every turn until it saves. Against something with bad Wisdom it is a slow, ugly death sentence.

Spell description: Haunt a creature with illusions of its greatest fears. It takes 4d10 Psychic damage each turn, cannot move, and has Disadvantage on Ability Checks and Attack Rolls.

Spell properties

• Damage: 4d10 Psychic per turn
• Damage type: Psychic
• Range: 18m (60ft)
• Duration: 10 turns
• Concentration spell
• Save: WIS save
• Conditions applied: Phantasmal Killer (Frightened). The creature cannot move, takes 4d10 Psychic at the end of each turn, and has Disadvantage on Ability Checks and Attack Rolls.
• Cost: Action + Spell Slot
• Recharge: Per action

Spell upcasting

Deals an extra 1d10 Psychic damage per turn for each spell slot level above the 4th.

How to obtain Phantasmal Killer

• Wizard at Class level 7
• The Hexblade Warlocks at Class level 7

Source item: Scroll of Phantasmal Killer

When to cast Phantasmal Killer

Cast it on a single dangerous melee enemy with poor Wisdom. It cannot move, so if it is not already next to your party it just stands there taking 4d10 a turn. Brutes, beasts, and constructs with a Wisdom score are the ideal targets.

The damage is Psychic, which almost nothing resists, and it ticks every turn for as long as the save keeps failing. Over three or four turns it out-damages any single-target spell you could have cast instead.

It is Concentration, and the target repeats the save every turn, so the value depends entirely on how bad their Wisdom is. Against a cleric or a mind flayer it will end after one tick. Check the target before you commit.

Frightened immunity does not protect against it. The wiki confirms it ignores things like Countercharm, so it lands on enemies who would shrug off Fear.