Any tips for homebrewing boss monsters?

[Rfkannen]

5e is not perfectly set up for boss monsters, it really is set up for using a lot of monsters per encounters.

The current campaign I am running I pitched as being kind of like the witcher, with a lot of monster hunts. So far they have done 2 big hunts, one against a scarecrew and once against an ogre (both heavily homebrewed) the first fight went almost perfectly, the second they killed in a single round.


There are two more monsters they have heard of that I am going to homebrew, the first is a Gargantuan spider, the second is a litteral hill giant (that looks like a hill when not in motion). I want these to both be good fights. The spider will probably have smaller ally minions, but the giant is alone. pcs are currently level 4 for context.

Any tips for homebrewing good boss fights? Any tips for these specific monsters?

[Dienekes]

I've been using Matt Colville's Action Oriented Boss monsters and it's worked fairly well so far.

The big problem with boss monsters is action economy. With boss monsters, assuming they even get to take their action, afterwards every PC gets to take their action before the boss gets to go again. For a party of reasonable size everyone focusing on one creature for a round usually kills it unless it's a huge HP sponge which generally isn't all that fun.

So I really suggest you give them Legendary Actions that are very flavorful and importantly change the shape of the battlefield in some way.

Having your Giant able to smash the ground and create a crater that your heroes will need to jump across is cool, memorable, and changes the battlefield.

Getting the Giant Spider to coat a huge area in webbing that slows and possibly binds some members of the party is the same.

The one thing you don't want to do is just have it stand there and take hits and then make attacks.

The most successful Boss Monsters I've ever used on my players I designed similarly to puzzles. The one that comes to mind was a Bulette that dived into and then burst out of specific holes in the ground 1 round later. Each hole was paired with another. After a few attempts they were able to figure out which of the holes were paired together and could plan to kill the thing accordingly.

Finally I would suggest making these creatures attack a bunch of the PCs without dealing too much damage to any one of them per round. Having the big beafy boss able to just kill one PC per turn is not fun (usually though I don't doubt someone can make it work).

But if say the Giant smacks everyone in a 5 by 15 rectangle with his club, that's a way to spread the damage around so that everyone should be running scared and hopefully then try to figure out a way to arrange themselves to avoid this damage.

Or the Spider can make attacks with each of its legs, but because they're all so far apart on their body they can only attack any one opponent with one leg per attack action.

Just try to think of ways to make them fun and exciting for the players.

[LordCdrMilitant]

5e is not perfectly set up for boss monsters, it really is set up for using a lot of monsters per encounters.

The current campaign I am running I pitched as being kind of like the witcher, with a lot of monster hunts. So far they have done 2 big hunts, one against a scarecrew and once against an ogre (both heavily homebrewed) the first fight went almost perfectly, the second they killed in a single round.


There are two more monsters they have heard of that I am going to homebrew, the first is a Gargantuan spider, the second is a litteral hill giant (that looks like a hill when not in motion). I want these to both be good fights. The spider will probably have smaller ally minions, but the giant is alone. pcs are currently level 4 for context.

Any tips for homebrewing good boss fights? Any tips for these specific monsters?

Battlefield, battlefield, battlefield. The combat area is as much of a part of a fight as the monster and it's abilities. A climbing monster, like the spider, might have a lot of vertical space to move in from both webs and trees/cave that give it extensive maneuver options the party has to deal with and traps for them to evade.
They should not be able to engage the target every single round. More turns should be spent maneuvering or using abilities to suppress target maneuver options than actually hitting the target.
Just whacking the target with the attack action probably shouldn't also achieve the desired effect. Perhaps it has a shield, can only be damaged in one area which it's protecting, or something so that the early part of the fight isn't just hitting it, but opening it up to be hit.


The thing you shouldn't do is just give it "bigger numbers". The "moar meat" solution doesn't make the encounter more tactical, suspenseful, or fun, neither does adding damage dice. The key to more tactics, suspense, and fun is to have things happen other than repeatedly whacking it and have it be more of a puzzle in coordination than an exercise in die rolling.

[J-H]

-Increase hit points if needed
-Use legendary actions, including debuffs (Vicious Mockery when missed, for example) and appropriate self-heals
-Use terrain (difficult, concealment/cover, 3-d movement and obstacles) to prevent everyone getting a clear optimum shot in Round 1. Have the boss use this also.
-Minion monsters.
-If it's a short adventuring day, make it hit like a truck so that the party feels like they were in danger too.
-Consider a 2nd set of actions. For one boss, he's part caster & part melee, and a built-up threat...so he gets one spot on the initiative where he takes a full round of actions as a caster, and then another spot later where he takes a full round of actions as a melee attacker.

[Dr. Cliché]

I'm by no means an expert but here's what I've learned thus far:
- It's often better to aim for attacks or abilities that will injure several PCs than ones which will take one or two PCs out of the fight. This isn't to say that there shouldn't be a risk of death, just that being forced to basically sit out the fight because the boss cast Hold Person on your on round 1 isn't much fun for that player.
- Action Economy is important. Legendary Actions have already been covered but I think it's important to stress that they aren't the only way to go about it. As an example, I had a boss fight not too long ago involving a giant worm, where the worm's head and tail acted at different initiative steps.
- Outside of very logical/telegraphed immunities, I think it's better for monsters to resist or recover from effects than to avoid them entirely. Hence, I try to avoid using Legendary Resistance whenever possible as I believe it's one of the worst-designed and least-fun mechanics to ever exist.
- Terrain is very important (and, if I'm honest, something I don't always pay enough attention to). Basically, try to avoid having monster fights in what amounts to a flat room or empty field. Instead, have terrain that makes things better for the boss and awkward for the players. Have them fight a Kobold Sorcerer in a room full of traps. Have them fight a giant spider in a room filled with webs, so that it can climb all over the place and they have to either waste actions cutting through them or else risk getting stuck.
- Consider adding 'stages' to a boss fight. Have the boss change in some way when it's hp drop below a certain threshold or even when it's killed. I think this can be a good way to mix things up mid-fight. It can also be used to potentially shake any negative effects currently afflicting the creature (another alternative to Legendary Resistance).
e.g. perhaps the spider initially fights the PCs normally, but when reduced to 50%hp it scuttles up one of its webs and begins dropping down on a line of webbing from the ceiling, biting, and then crawling back up the web. I think little things like that can really change the dynamics of a fight.
- Specific one for the hill giant - have you considered waiting for the players to be on its back before it animates? Maybe give them the choice of hanging on or jumping off as it starts to get up.

[Danielqueue1]

For the literal hill giant I recommend something I used to a great deal of fun in my campaigns, have it he an unfairly difficult boss fight, but have all of its moves telegraphed the previous round. At the end of each of its turns you give some hint as to what it is going to do next. The archer critically hit it during the round? On its next turn it finishes swinging its tree, then turns to glare at the archer. Will it throw the tree hitting everything in a wide area of where the archer was at the start of its turn? Will it do a foe-tossing charge smashing everything in its way? Party will have to spend some time moving, shifting and maybe flat out running away because they have an idea of what's coming, but unlike most turn based games, can actually do something about it turn by turn.

[MrStabby]

Start with the out of combat abilities. These will determine how the monster will set it's trap of seek out the PCs. Tension happens when the PCs are being hunted - not when they can be guaranteed a fight on their terms after a long rest. A great fight relies on context.

Make your monster versitile. If you want everyone in the party to have a meaningful role in it's defeat you want to make sure that there is no single ability that will simply shut it down. So you don't want anything so slow that a lone archer can kite it to death.

Defensive abilties are good, in a broad sense. 3 times per day misty step. 5 HP per round regeneration. Shield spell. Monster version of cunning action. Fog clouds... Defensive abilities should fill two roles: they should let both endurance and nova characters shine in the battle, not just one of them and they should make the battle last long enough that the monster gets to showcase its abilities. Even things like a chance to inflict a short lived poisoned condition on an enemy to slow down damage is nice.

Legendary actions are awesome. I usually go for one offensive option, one defensive and one mobility one. The defensive one includes control effects - if you can push away and knock down two of the party for a turn then the damage your monster might take is seriously reduced. Lair actions are also very cool and can be really atmospheric.

Give them a magic weapon if appropriate. I am a bit rubbish at this - showcasing your loot before surrendering it to the PCs can add to the thrill of ownership. Also, it is a great consistant way to add unexpected abilities.

Depending on campaign style/player desires, consider not just average damage but also the variance. Pushing more power to recharge abilities makes the PCs hang on that die roll each round to see how much trouble they are in. Expanded critical range means that players always feel at risk - there is a non negligable chance that damage could be way above what might be expected. This can add great tension, but isn't for every table. It's a boss monster - if a PC dies to it is is at least an epic death.

Spread your abilities to target different weaknesses. One of the nice things about the Three Strong Saves/Three Weak Saves system that 5th ed uses is that broadly speaking it means you only need 3 abilities targetting different saves for each player to have at least one thing they are good against: so consider a set of abilities spanning Con, Wis, and Dex OR a set targetting Cha, Int or Str but less often splitting between the two groups. This should give everyone something to fear and something to be thankful for.

[Throne12]

It's all about hp and action economy. If you have the party fight one monster as a boss. You should give it hp =monsters hp × number of PC's. Then give it legendary actions. My party fought a demon in a arena. It had strong melee and spells. So I gave it one turn to only do melee damage then a pc then a round for a spell then pc. It had LA to cast cantrip, heal a small but, dash action.

[LordCdrMilitant]

As a consideration, if it's big enough, you could do for the Hill Giant to do a "Shadow of the Colossus" type thing, where the boss is the battlefield and the objective is to make lots of skill checks to reach the weak points, while it tries to defend itself by swatting/shaking them off or the likes.

[krazedkoi]

First, I love what you’re doing! I’ve played in and run games in the same spirit and some encounters can be incredibly fun (and now and then DM wiffs and someone doesn’t have fun).

I think folks above have given solid general advice so I’ll try to be specific to your monster ideas.

The Spider
- 100% give it mook spiders!
- What kind of spider is it? Does it build a web? Is it like a trap door spider? Or a speedy stalker like the Huntsman?
- It has terrain advantage, they’re coming into its home. Consider the parties methods of approach and the spider’s defences. Does it make traps or alarms? Give it tremor sense, if it builds a web it can sense the vibrations and makes it less likely to be surprised. For non-web building spiders, most of them are still very sensitive to vibrations or sound as they’re still usually ambush predators.
- They’re not just on its turf, they’re in its hunting ground. Remember that!
- also really put yourself in the spider’s 8 legs and think about how often does it really “relax” or even sleep? This thing has set up shop here just because there’s free lunch, it’s an old spider (or at least a successful one), so play it cunning.
- abilities should include extra attacks, possibility some kind of spawning ability or breath weapon (web, poison, acid), extra-ordinary senses

The Hill Giant (I really like this!)
- a bunch of the previous replies had really cool synergistic ideas: An AoE slam that generates difficult terrain, an AoE melee attack, telegraphed actions is just a great idea if you think you can make it work.
- When making solo mobs I like to think of them as a character in a fighting game. Bonus actions are light, actions heavy, etc. How do you want these to chain together? What are some of the giant’s combos?
- I think it would be cool if his back (the hill) is essentially that, so give it its own HP pool and once the party has literally dug through it, it can finally be damaged.
Also, with the slam, the user had suggested it shakes its self and rocks fall, as an additional threat, and to even out economy of action, have an added effect that if they fail the dex save for half then they are also both prone and pinned, and will need to spend an action digging (or an ally can spend an action digging) to be freed from the rubble.
This way you can keep the damage low (and not just blat the mispositioned caster) and really muck up a round for the frontline damage dealers.
Your monster lives longer, more players get to do more things, you chew through more resources and force people to get creative with their builds, and for a round or two, everyone should feel a little bit of pressure and sweat.
- how intelligent is the giant? Does it try to run or flee if it starts losing? Are they 100% supposed to kill it or can they make it surrender? (I gravel at your feet!)

I hope you and your party have a tonne of fun with this!!