Cloudkill — Complete D&D 5e Spell Guide

Table of Contents

• •Quick Answer
• •Overview
• •Stat Block
• •When NOT to Use
• •Comparisons
• •Spell Slot Efficiency
• •Pro Tips
• •Common Mistakes
• •Usage Tips
• •Synergies
• •FAQ

Overview

Hey, new caster buddy—Cloudkill is a 5th-level conjuration spell that's been in my toolkit since 3e, but in 5e it's firmly Situational. You drop a 20-ft radius yellow-green fog ball at 120 ft range (1 action, V/S, concentration up to 10 min), heavily obscures, spreads corners, moves 10 ft away from you each turn, sinks low/pours down holes. Creatures entering or starting turn inside CON save or 5d8 (avg 22.5) poison damage, half on success—even if holding breath or no breathing needed. Upcast +1d8/level above 5th. Verdict: Mediocre damage for a 5th slot (Fireball upcast to 5th does 10d6=35 avg), poison resistance/immunity everywhere at tier 3-4 (dragons, undead, devils, oozes), but shines as area denial in dungeons forcing chokepoints or herding mobs. Opportunity cost high—skip for control kings like Wall of Force. Veterans love it for minion-mulching in tight spaces, but it's a trap if your DM runs open fields or poison-immune heavies. Total word count across guide ~1250.

Stat Block

When NOT to Use This

• •Open battlefields where DM can 'strong wind' it away in 1 round.
• •Flying-heavy encounters—hugs ground, wasted.
• •Poison-resistant/immune groups (undead, constructs, dragons)—damage halved to nothing.
• •When you need burst: 22.5 avg loses to 5th Fireball's 35.

Spell Slot Efficiency

When worth the slot: Minion hordes in dungeons; 10 zombies = 225 potential damage over duration.

When NOT worth the slot: Boss fights or outdoors; better single-target or immunities.

Pro Tips (Veteran Secrets)

Tip #1: Track enemy positions via echoes or tremorsense allies; obscured doesn't block blindsight.

Why veterans know this: Blindsight (bats, dragons) ignores fog—position so they walk into it anyway.

This avoids the mistake of: Assuming total invisibility; vets use it to hide own positioning.

Tip #2: Upcast to 9th for 9d8=40.5 avg in desperate horde wipes.

Why veterans know this: Sorlocks twin lower but Cloudkill can't twin; upcast beats multiple slots.

This avoids the mistake of: Wasting lower slots on weak AoE—save for this nuke.

Tip #3: Dismiss early if enemies flee; reposition for round 2.

Why veterans know this: 10-min duration tempts holding, but fights end in 3 rounds avg.

Common Mistakes to Avoid

Casting in open fields.

Why it's bad: Wind disperses instantly per DM fiat; zero value from 5th slot.

Do this instead: Scout for enclosed terrain first; have Wall of Force ready.

Expecting damage vs dragons/undead.

Why it's bad: 90% tier 3+ bosses immune/resist poison; averages 0-11 damage.

Do this instead: Prep Synaptic Static or Circle of Death instead.

Standing still post-cast.

Why it's bad: Fog moves away from you—forces you to follow or waste coverage.

Do this instead: Stride back 30 ft/turn, herding it into new targets.

Usage Tips

• •Position the center to maximize overlap on clustered enemies in 10-ft corridors—covers ~1256 sq ft but sinks, so drop on stairs to flood below.
• •Cast then kite back 10 ft/turn to keep it pushing into foes; synergizes with your movement to control battlefield flow.
• •In lairs with low ceilings/openings, let it pour down pits or stairs for surprise damage on hidden foes below.
• •Upcast only if desperate for more damage; usually better to save 6th+ slots for Hold Monster or Chain Lightning.

Rules Notes

• •Fog is heavily obscured, granting total cover vs sight-based attacks through it.
• •Moves 10 ft away from caster each of THEIR turns, hugging ground and sinking to lowest level—perfect for multi-level dungeons.
• •Affects all creatures regardless of breathing; RAW no immunity clause beyond save.
• •Upcasting adds 1d8 per level: 6th=6d8 (27 avg), but still poison typed.

Synergies

• •Wall of Stone (5th) to seal ends of corridor, trapping horde inside fog for repeated saves.
• •Sickening Radiance (4th)—stack for exhaustion + poison, enemies can't escape without massive damage.
• •Web (2nd) or Grease (1st) to prone enemies, lowering their CON saves via prone disadvantage if applicable—no, prone doesn't disadvantage CON.
• •Hypnotic Pattern (3rd) to paralyze first, then fog for auto-fails on paralyzed (incapacitated don't move, but starting turn saves).

Anti-Patterns

• •Don't center on single boss—5d8/turn too low vs immunities, wastes concentration.
• •Avoid open air fights—'strong wind disperses' lets DM narrate gusts ending it early.
• •Never cast vs flying enemies above 10 ft; it hugs ground, they ignore entirely.

Tactical Modules

• •Chokepoint Herder — When to use: Narrow dungeon halls or bridges with 10+ low-CR minions (goblins, zombies).. Synergy: Push fog into them while allies hold the other end; averages 11-22 damage/turn per foe over 3 turns.
• •Lair Flooder — When to use: Verticality like castles/stairs/pits; enemies below unaware.. Synergy: Pour down openings after scouting with Familiar; catches melee mobs flat-footed.
• •Boss Minion Clear — When to use: Boss + adds; peel minions while tank distracts boss.. Synergy: Bigby's Hand (5th) grapples boss away; fog chews guards for 67 avg damage over 3 turns to a single target.

Countermeasures

• •Threat: Flying enemies ignoring ground fog. — Response: Switch to Fireball or upcast Shatter; position to catch low-flyers.. Fallback: Dismiss concentration, recast Synaptic Static for psychic AoE piercing immunities.
• •Threat: High-wind outdoor battlefield. — Response: Cast Wall of Force first to enclose area, then Cloudkill inside dome.. Fallback: Fall back to single-target like Cone of Cold.
• •Threat: Poison-immune boss charges caster. — Response: Dimension Door 500 ft away, let fog slow pursuit.. Fallback: Counterspell incoming, then Bigby's Hand to restrain.

Frequently Asked Questions

Is Cloudkill good in 5e?

Situational. Excellent area denial vs low-CON minions in enclosed spaces; poor vs bosses/immunities. Prep over Stinking Cloud for pure damage.

Does Cloudkill work underwater 5e?

Yes—it's fog/vapors, not relying on air; sinks in liquid too per 'lowest level.' Great vs aquatic humanoids without water breathing immunities.

Can you twin Cloudkill 5e?

No—targets area, not creatures; Twinned Spell only for single targets. Use Quickened for double action economy instead.

Cloudkill vs Stinking Cloud which better 5e?

Cloudkill for raw damage (5d8 vs 4d8); Stinking for incapacitate control. Cloudkill upcasts better, but Stinking cheaper slot.

Does Cloudkill work on undead 5e?

Damage yes, but most undead immune to poison—check statblock. Affects no-breathe creatures RAW, but immunity blocks.

Is Cloudkill concentration 5e?

Yes, up to 10 min. Drop if better control opens; vets dismiss after 2-3 rounds.

Cloudkill build 5e wizard?

Conjuration Wizard (Benign Transposition to reposition fog). Pair with Wall spells for traps; Sorc for Metamagic flexibility.

Does Cloudkill stop invisibility 5e?

No—reveal invis with See Invisibility first; fog obscures sight but not presence.

Citations: api:spells/cloudkill

Includes SRD content per CC BY 4.0. Source: dnd5eapi.co.