Most complex monsters to run as a DM in 5e?

[HoboKnight]

What are the most complex official monsters to run in 5e? Imo its Mage/Archmage(all the spells), adult dragons(legendary actions, lair actions), vampires(ton of abilities).

What else? What did I overlook?

Thanks

[J-H]

Usually spellcasters, which is why when I'm writing stuff, I have switched from:


Shaft
Medium Humanoid
AC 19 (Elven Chain Shirt + DEX + Dark Blessing)
HP 180
Speed 30 ft.
STR 12, DEX 14, Con 18, INT 19 (item), WIS 20, CHA 16
Str Dex Con Int Wis Cha
12(+1) 14(+2) 18(+4) 19*(+4) 20(+5) 16(+3)
Saves Str +4, Dex +5, Con +7, Int +7, Wisdom +13, Charisma +11
Skills Perception +9, Deception +7, Religion +9, any two other appropriate skills;
Senses Passive Perception 19
Dark Blessing Shaft gains his Charisma modifier as a bonus to his Armor Class & Saving Throws
Quick Stab Shaft may make a single melee attack as a bonus action.
Actions
Heart-Taker Dagger+2. Melee weapon attack, +9 to hit, 5’, 1d4+4 piercing; on crit, +2d12 damage & empower next spell (see item description)

Spellcasting. Shaft is a 16th-level death priest. His Spell attack roll is +10 and his Spell save DC is +18.
Cantrip - with +WIS to damage - Toll the Dead (60’, Wis save or 3d8+5 or 3d12+5 damage if target injured), Sacred Flame (Dex save or 3d8+5 radiant), Light
1st ()()()() Bane (C, 30’, 3 targets, -1d4), False Life (1 hr, 1d4+4 temp HP), Command (60’, 1 word command), Guiding Bolt (120’, ranged spell attack; 4d6 dmg, next attack gets advantage), Sanctuary (1 min, Wis save or cannot attack; but warded creature must not attack or ends), Shield of Faith (C, +2 AC), Inflict Wounds (melee spell attack, 3d10, upcast 1d10/level)
2nd ()()()() Ray of Enfeeblement (C, 60’, ranged spell attack; on hit, deal only half damage with Str-based weapon attacks; Con save at end of each turn to break), Blindness/Deafness (1 min, 30’, Con save; repeat save at end of each turn to negate; upcast, 1 creature/level), Hold Person (C, 60’, Wis or Paralysis; upcast +1 target at 3rd; recheck each round), Spiritual Weapon (1 min, melee spell attack 1d8+5; bonus action each turn to repeat; upcast 1d8 per 2 levels higher)
3rd ()()() Vampiric Touch (C up to 1 minute; melee spell Attack, 3d6 necrotic; heal half; repeat as attack action; upcast 1d6/level), Magic Circle, Protection from Energy (C, resist 1 elemental type), Dispel Magic (single target, autowin 3rd level & below; remainder is ability check vs DC 10+SL), Bestow Curse (C, Wis or cursed; 5th level or above removes C requirement; best curse is Wis @ start of each turn or lose turn)
4th (X)(X)(X) Blight (30’, 8d8 necrotic, Con half; upcast 1d8/level), Death Ward (8 hrs, prevents dropping to 0 from damage, then expires; OR negates an instant-kill that doesn’t deal damage), Banishment (C up to 1 minute, Cha or banish-incapacitated-until spell ends; upcast 1 target/level), Freedom of Movement (No slowing, paralysis, restraint, etc.), Guardian of Faith (8 hrs; Large spectral guardian occupies space; looks like sword and shield; any creature moving within 20’ of guardian takes 20 radiant damage, Dex save half; guardian vanishes after doing 60 points of damage)
5th ()(): Antilife Shell (C, 10’ radius, prevents living creatures from entering; no save; if you move to force a creature through, effect ends), Insect Plague (C, 20’ radius, light obscure & difficult terrain, 4d10 enter or end turn, Con save half; upcast 1d10/level) Contagion (Melee spell, Con save or disease)
6th (X)(): Harm (60’, 14d6 necrotic, half on CON save; if fail saved, damage dealt reduces max hp for 1 hour or until disease removed), True Seeing (1 hr, see Invis/Ethereal/etc. 120’), Word of Recall (Teleport to sanctuary spot)
7th () Inflict Wounds (9d10 damage)
8th () Earthquake (cast at 0 hp)

Bonus Action
Heart-Taker Dagger+2. Melee weapon attack, +9 to hit, 5’, 1d4+4 piercing; on crit, +2d12 damage & empower next spell (see item description)

Reaction
Shaft may negate a critical hit on himself 5 times per day ()()()()()
(plus Legendary Actions)


to


Aarakocra Senior Priest
Medium Humanoid
Armor Class 16 (Breastplate)
Hit Points 126
Speed 20 ft., fly 50 ft.
Str Dex Con Int Wis Cha
12(+1) 14(+2) 12(+1) 12(+1) 18(+4) 14(+2)
Saves Wis +8, Cha +6
Skills Perception +12
Damage Resistances Fire, Radiant
Senses passive Perception 22
CR 9
Dive Attack. Gain +2 to hit and +1d6 to damage on the first melee attack made immediately after descending 10’ towards the target.
Keen Sight. Aarakocra have Expertise in Perception.
Actions
Corona of Light. The Senior Priest may, as an action, emit an aura of sunlight (60’ radius + 30’ additional dim radius). Enemies in the bright light have disadvantage on saving throws against spells dealing fire or radiant damage. This effect lasts for one minute.
Dagger. Melee Weapon Attack, +6 to hit, 5’, 1d4+2 piercing damage; +8 to hit if plunging, +1d6 damage if dive.
Spellcasting. The Senior Priest casts as a 15th-level cleric. Its spell attack roll is +8, and its spell save DC is 16.
Attack
Sacred Flame (60’, Dex or 3d8+4 radiant damage)
()() Guiding Bolt (120’, attack roll, 4d6 radiant, next attack has advantage)
()() Fireball (150’, 20’ radius, 8d6 fire damage, Dex half)
()()() Inflict Wounds (melee spell attack, 6d10 necrotic)
() Dawn (C, 60’, 30’ radius/40’H cylinder, 4d10 radiant damage, Con half on appearance and ending turn in space; relocate as a BA)
() Harm (60’, 14d6 necrotic, Con half, can’t take to 0hp; reduce max HP for 1 hr)
() Fire Storm (150’, 10 10’ cubes adjacent to each other; 7d10 fire damage, Dex half; damage objects)
() Inflict Wounds (melee spell attack, 10d10 necrotic damage)
Buff
() Sanctuary (BA, 1 min, Wis or must retarget)
Debuff
() Calm Emotions (C, 60’, 20’ radius sphere),
() Hold Person (C, 60’, Wis or paralyze)
() Hold Person (C, 60’, Wis or paralyze, 3 targets)
Heal
()() Cure Wounds (Touch, 3d8+4)
Other
()() Dispel Magic (120’, 3rd or lower dispelled, higher d20+4 vs. 10+spell level),
() Word of Recall (conditional teleport to safety)


Bonus Actions
Spiritual Weapon A spectral dagger attacks a target within 30' of the war priest. Melee spell attack, +8 to hit for 1d8+4 force damage.
Reactions
Warding Flare. Once per round, when a creature visible to and within 30’ of the Senior Priest or one of its allies, the Priest may use its reaction to impose disadvantage on the attack roll by causing light to flare in front of its eyes. A creature that can’t be blinded is immune to this feature.



Swapping from "everything by number" to "everything by category with a set number of uses per spell makes it easier to pick options.
I also found that in larger battles, it's very hard to remember reactions that are triggered by others, like the Light Cleric "Warding Flare" ability.

Vampires have a ridiculously long statblock, but half of it's irrelevant. Shapechanger only comes up at the start or end of the battle, Misty Escape happens once per fight if that, Vampire Weaknesses is very specific, and Children of the Night is very situational versus charming or attacking.

[Witty Username]

An honorable mention to large groups with a mobility option, shadow demons and goblins can get hectic to pilot very quickly. spell casters at least can identify a line for a combat for planning, group fights tend to require more adaptive thinking if they have more than rush and attack.

[Trask]

An honorable mention to large groups with a mobility option, shadow demons and goblins can get hectic to pilot very quickly. spell casters at least can identify a line for a combat for planning, group fights tend to require more adaptive thinking if they have more than rush and attack.

I've never been a fan of the pseudo-cunning action for goblins. Like you mentioned, it feels busy to run for such a simple enemy.

[LudicSavant]

What are the most complex official monsters to run in 5e? Imo its Mage/Archmage(all the spells), adult dragons(legendary actions, lair actions), vampires(ton of abilities).

What else? What did I overlook?

Thanks

Pretty much all the traditional (pre-MPMM) spellcasters are good examples. Volo's Necromancer for example.

Also, look for monsters that have variants. They often add additional depth and complexity. Variant Drider is much more interesting than normal Drider, for example. Variant dragons get spellcasting (in the MM) and more options for senses and such (in FTD).

[PhoenixPhyre]

Not specific monsters, but generally the things I have the hardest time keeping track of are (in no particular order):

- interrupts (ie off-turn actions) specific to a creature. This includes aura effects that trigger when someone else starts/ends their turn within a certain distance (etc). I'd rather have active abilities that have riders, or things that trigger on the monster's turn.[1]
- spellcasting, mainly due to presentation. Having a huge list of spell names only and way more spell slots than a monster will ever use in an encounter, plus having to infer how much the cantrips will do means that having more than one spellcaster per encounter starts to bog things down a lot.
- heavily conditional mechanics. A monster does X damage with their attack if Y, but if Z then Q, except where listed in trait T...Having blanket "the monster's attacks deal 2d6 extra radiant damage, included in the attack line" is fine. But the added complexity of, say, versatile weapons (d6 unless two hands, then d8, say) is unneeded IMO.

In general, I strongly prefer[2] having more monsters per encounter, each of which is simpler, rather than one or two big complex beasts I need a flowchart to do right with. Each monster should have 1-2 Big Things and then some fillers. If nothing else, that guarantees they can get their Big Things off as long as they get even one turn. Encounter complexity comes from composition (ie aggregating different, often complementary, monsters, each with their own ability set) rather than having deep and complex single points of failure. A monster with a 5-turn wombo combo is going to be unsatisfying most of the time, because it will die well before it gets that combo off.

[1] interrupts in the hands of players is fine, however. For a few reasons--they're the ones who have to track those, their triggers, etc. And the players should get to feel special, especially since each one only has one "body" to play. I've got dozens across an adventuring day (or maybe even in a single encounter!)--if I need to take more actions as a DM to make things balance, I'll just add in more monsters.

[2] And I accept that this is totally personal, subjective preference. YMMV, and that's fine.

[Dork_Forge]

I really enjoy using star spawn, and part of the appeal is how they play together.

However, remembering all of their different features and how they fit together can be a struggle some sessions.

[Witty Username]

- interrupts (ie off-turn actions) specific to a creature. This includes aura effects that trigger when someone else starts/ends their turn within a certain distance (etc). I'd rather have active abilities that have riders, or things that trigger on the monster's turn.[1]


That definitely tracks, the most consistently forgotten monster trait at my table has been legendary resistance.

[MarkVIIIMarc]

Oh my. Ueah, some of the mechanics can be a thing.

Honestly though high INT or WIS monsters are tough. I am intimidated by having to make as good of a choice as they would and frequently settle for using DM meta knowledge.

[stoutstien]

Strahd takes the cake for me. No only is his block bloated you are basically in constantly contact with the party so the "snapshot" mentality fails.

Also running long duration charms suck.

[KorvinStarmast]

I really enjoy using star spawn, and part of the appeal is how they play together.

However, remembering all of their different features and how they fit together can be a struggle some sessions. Concur. I have used star spawn quite a bit in tier 2 sessions. And yes, I needed to make a little cheat sheet/smart card to get their act together.

Monsters who have reactions can be a handful, particularly if their reaction is a lot like a spell (Volo's Warlock of the Archfey being one such).