Using Matt Colville’s Action Oriented Monsters

I like Matt’s video on action-oriented monsters, but I haven’t got a chance to test it out yet. Let’s build a solo monster for a level 5 party and see how it turns out!

I want to make a pulpy sci-fi/horror monster. Something to terrify my players, and that they can feel good about killing at the end of the encounter. I like John Carpenter’s The Thing So I’m gonna draw inspiration from that.


The idea is to draw inspiration from The Thing, not to perfectly reproduce it. Let’s narrow down our focus to just a few things. I don’t want any philosophical or moral dilemmas, just Vaseline covered practical effects to gross my players out and let them go nova on something unambiguously evil.

  • Shape changing/dividing
  • Assimilation
  • Teeth and Claws and Flesh


Black Pudding Stat block seems like a good place to start. I’ll Rename Alabaster Flan. I like the low AC (the fun stuff happens when it gets hit) but I’ll triple the HP since it’s going to be the only thing the party is attacking and I want it to survive more than a round or two.

  • Alabaster Flan
  • Large Ooze
  • AC 7
  • HP 255
  • Speed 30, Climb 20

I like Black Pudding’s condition immunities, but I don’t think damage immunities would be fun in this context. Let’s get rid of the damage immunities then add vulnerability to fire and lightning. It will feel awesome when the players get to burn these things to a crisp.

  • Damage Vulnerability fire, lightning
  • Condition Immunities blinded, charmed, deafened, exhaustion, frightened, prone
  • Blindsight is a cool ability, but my Flan can also grow eyes and ears so I don’t think it should rely only on that. I’ll cut blindsight in half then give it darkvission.
  • Senses blindsight 30 ft, darkvision 60 ft


The Ooze abilities amorphous and spider climbare pretty good for us as is.

  • Amorphous. The Flan can move through a space as narrow as an inch wide without squeezing.
  • Spider Climb. The Flan can climb difficult surfaces including upside down without an ability check.

Corrosive abilities don’t really match up with Carpenter Flan theme. I’ll tweak Corrosive Form to have better flavor.

  • Dangerous Form. No matter where you attack, Carpenter Flan grows teeth and claws that clamp down on your arms and weapons. A creature that touches the Carpenter Flan or hits it with a melee attack from within 5 feet takes 1D8 piercing damage.

I want this monster to split into two smaller oozes every time it gets hit. However, I don’t want to have to keep track of an entirely different stat block for each size category. I’ll throw in some rules here that will hopefully make my life easier when it starts dividing and I’ve got a bunch of these things out on the table all at once.

  • Size Matters. All attack rolls made against targets two size categories smaller than the Flan is made with advantage. If the Flan would deal damage to a target that is two size categories larger than it, the target takes half damage instead.


The Campbell Ooze doesn’t really have pseudopods so much as it’s constantly growing new mouths and claws to attack with. I’ll give a multiattack instead of a pseudopod attack. I also want to be able to take advantage of the spider climb ability, so I’ll give it a drop attack. Finally, I feel like my monster is going to struggle against ranged opponents, so I’ll give it a lunge attack to help it close distances.

  • Multitrack. Flan makes one claw attack and one bite attack
  • Bite. +5 to hit, 1D8+3 piercing damage. Target must make a DC 12 Strength Saving Throw or be grappled
  • Claw. +5 to hit, 2D10+3 slashing damage
  • Drop. Flan attacks one target at least 5 ft. directly below it. +4 to hit, 1D8+3 piercing damage. Add +1D8 Damage for each additional 5 ft the Flan drops, up to 30 ft (6d8+3). Target must make DC12 Strength Saving Throw or it becomes grappled.
  • Lunge. The Flan grows the necessary appendages, then jumps, flies, or otherwise hurls itself up to 15 feet. It may make a claw attack on one target within 5 feet of its landing position.

Bonus Actions

I want my monster to be able to do cool things other than just attack each round. I’ll give it the hide action so it can pop out from around corners and under chairs. Then, I’ll give it something to emphasize the shape changing theme.

  • Hide. Flan may hide as a bonus action
  • Assimilate. If a grappled target is within 1 size category target must make a DC 17 constitution save or take 1D6 damage and be thrown 5 feet in a random direction. Flan moves 5 feet in the opposite direction and is indistinguishable from the target until it is dealt damage.


The Flan only has one reaction, but it’s the heart of this encounter.

  • Split. When a Flan is tiny size or larger, has at least 10 HP, and is subjected to lightning or slashing damage it splits into two new Flans. Each Flan has half the original Flans HP rounded down and is one size category smaller.

Villain Actions

Villain actions are like legendary actions or lair actions. They are things that don’t happen on the monsters turn but influence the scenario to benefit the monsters.

Round 1

  • Ambush. Flan starts off looking like a dog or some other innocuous animal until it makes its first attack

This is already a pretty tough monster so on the first round of combat, so I don’t want to do anything too crazy on the first round of combat. Ambush isn’t quite a true villain action since it doesn’t really give an extra thing for the Flan to do but it will help with positioning and to set the tone for the encounter.

Round 2

  • Scatter. Each Flan may take a move action without provoking an attack of opportunity

I am hopping by this point the Flan the Flan got hit a bunch of times and the party are rapidly becoming surrounded by a bunch of smaller Flans. I want an ability to help them reposition all my new units. I might use this early in the if I need some Flans to escape attacker or are otherwise bad positions. Ideally, I’d use this at the end of the round so all the Flans can get in their attacks then scatter to make the players chase them down.

Round 3

  • Regeneration. Each Flan that hasn’t been dealt damage at the end of this round regains 30 HP and increases a size category

This ability might be unbalanced depending on how many Flans are left, and the condition of the party. If I was running this monster I’d probably adjust it on the fly to make sure I don’t TPK but I want an emotional reaction from my players. Maybe instead of fighting a few of the regrown Flans escape and now represent a continuing threat to the party for the rest of the adventure.

Finished Product

Here is the Final Product all polished up:

I had a lot of fun making the Alabaster Flan, and it’s definitely a monster that I would be excited to put in front of my players! I honestly have no idea how balanced this is against a party of 4th level players. the damage output is high,but fair. However, it’s much harder to predict the outcomes of the split ability in combination with the villain actions. I think that’s part of what makes this process cool though. The end result is going to be something that breaks expectations of how an encounter should work. I think that uncertainty pretty much guarantees a memorable battle one way or the other.

Leave a Comment

Your email address will not be published. Required fields are marked *