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5E Homebrew Golem for critique

Trit One-Ear

Hey all,

I'm still fairly fresh at making homebrew creatures, and don't have all the tips and tricks down to as CR guidelines etc.
For an adventure that leads my players to the depths of a volcano, I've created a new golem for them to face - Obsidian Glass. I know there are some Obsidian golem homebrews already out there, but none of them felt like they suited my needs, so I took a stab at making my own.

For CR reasons, I started with the Flesh Golem as a base, and removed most of the flesh-specific traits. I upped the AC, lowered the HP a bit (tried to bring both closer to average values) and added some fun traits lifted from other creatures.

Very open to feed back!



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Hey Trit! Good to see you on here again!

I'll tackle this one. First, I'll tell you right off that bat that it's not CR 5, probably more like CR 9 or 10.

Spell Reflection is a tricky trait, so our first step is to reverse engineer the spectator (beholder) to get a read on how much Spell Reflection influences Defensive CR and/or Offensive CR.

Step 1: Reverse engineering the spectator's CR
At 39 HP, and AC 14, the spectator's baseline Defensive CR = 1/4.

To determine its 3-round DPR, we'll assume it uses Wounding Ray twice per round. While this isn't strictly accurate, it's a fair approximation since paralyzation and confusion are pretty significant control (single-target fear less so). So that is 16 + 16 = 32 damage. With save DC 13, that means its baseline Offensive CR = 4.

Now, the spectator is described in the MM as a CR 3 monster. So the designers are interpreting Spell Reflection to boost either its Defensive CR up to 2, or its offensive CR up to 6, or – more likely – boosting Defensive CR to 1 and Offensive CR to 5.

So that's clear how Spell Reflection is interpreted for the CR 3 Spectator. But let's go one further step and evaluate what kind of magic the spectator is likely to be using Spell Reflection against. Well, it is CR 3, so the default assumption is a party of 3rd level PCs would be facing it. A typical 3rd level damaging spell might be shatter which deals 13 (3d8) damage. However, a 3rd level wizard only gets two 2nd level slots, so...

What if we increase its effective HP by 2 * 13 = 26? And increase its DPR by (13+13+0)/3 = 8?

Defensively, it now has 39 + 26 = 78 effective HP, and still AC 14, which makes its Defensive CR 1/2.

Offensively, its DPR now is 32 + 8 = 40, still save DC 13, which is Offensive CR 5.

Making it's total CR 2.5, or rounded up to 3.

Step 2: Applying this to the Obsidian Golem

It's approximately CR 5 – or that's what we're aiming for – so that means typical damaging spells it will be using Spell Reflection against are fireball or lightning bolt, which deal 28 (8d6) damage. Again, however, the wizard only has two 3rd level spell slots. So, I'm going to increase its effective HP by 2 * 28 = 56, and I'm also going to increase its DPR by (28+28+0)/3 = 18.

Step 3: Ironing out the kinks with "Sharpened Form" trait

Sharpened Form. Whenever a creature within 5 feet deals 20 damage or more to the golem in a single round of combat, a shower of glass, a shower of glass erupts, dealing 8 (2d6) slashing damage to the attacker.
Your intent with this is unclear.

Do you intend that, say, a spellcaster could hit the golem with a shatter spell and...nothing would happen?
In other words, do you only intend for this to trigger when a 5-ft melee attack hits the golem?

Also, you say "in a single round", but that would include off-turn opportunity attacks. Do you mean "in a single turn" (a cleaner way of also including opportunity attacks without the ambiguity)? Or do you actually mean "on that creature's turn" (hence excluding opportunity attacks)?

These questions will affect how often Sharpened Form gets triggered.

I'm just going to assume that it gets triggered once per round, thus increasing the golem's DPR by 8.

Step 4: Golem Maths

Now, the golem's Defensive CR = 11

Effective HP = (85 * 2 damage immunities for a CR 5-10 monster) + 56 damage foregone thanks to Spell Reflection = 226
Effective AC = 16 + 2 magic resistance = 18

And it's Offensive CR = 8

DPR = (13 + 13) multiattack + 18 Spell Reflection + 8 Sharpened Form = 52
Effective Attack = Should be +7*

*your stats list +6, but with Strength 18 and being a supposedly CR 5 (prof +3), that should be +7.

Thus, it's total CR = (11 + 8) / 2 = 9.5 which you can round up or down as you see fit.

Because it's a CR 9 or 10, you can still assume the x2 modifier for damage immunities. However, it's proficiency modifier is +4, so that will put its attack bonus at +8. That's not enough to change its offensive CR, but just want to make sure we get it right.

Final Thoughts
Because this is a golem that's more likely to face PCs of 9th level, you may wish to reevaluate how significantly Spell Reflection influences its CR. I made the assumption that the PC's offensive caster only had two 3rd level spell slots to throw fireball / lightning bolt at it twice during combat. However, if the party has 5th level spells, that could change things. Personally, I think just rounding it up to CR 10 would be good enough.


Trit. Thanks for sharing. I don't often disagree with @Quickleaf when it comes to monster design, but I am going to here. I think the CR is closer to 5 than it is to 9 or 10. You have basically made the flesh golem (CR 5) with a few extra bits. The only real differences are: Sharpened Form and Spell Reflection.

These do increase the CR some, but IMO it is limited. Sharpened from on damages creatures within melee range and requires the golem take 20 HP damage first (though I agree the wording is a bit odd as I assumed it was per strike). This level of damage is easily absorbed or avoided all together with ranged attacks. Spell Reflection is only available once per round (it is a reaction) and only if an attack misses or save is made. The golem has no saving throw bonuses, so it will miss a lot of saves.

I think CR 6 or 7 at most seems adequate.

However, I do suggest you give it ranged attack (maybe it can throw some shards). It really can't do anything against ranged weapon attacks and its slow speed (oddly 22 ft) means PCs can keep it a range without fear of attack. If it fighting a range heavy martial party, it is a CR 5 at best.


I would modify sharpened form to each melee hit dealing 1d4 or 1d6 damage. It is simpler that way and all the players will understand better.

The spell reflection power may not get used that much once the PCs know about it and the magic resistance power. It also seems a bit more since it already has spell resistance. I like the idea though, but think it could be changed a bit to limit it to spells like rays or magic missiles.

I would even add a burst or cone power that shot glass shards as an encounter power. Maybe something that shoots a 30ft cone dealing 5d6, save for half.

I might bump the CR to 6-7 based on this, but most of my PCs could kill this rather easily, and they are not that optimized. Also, my groups tend to all have magic weapons by level 5.

Trit One-Ear

Thanks for the replies all.

@Quickleaf - Honored you remember me! Appreciate all the work you put into your response. This level of thought in monster design is still pretty new to me, but you've made it super easy to see how you reverse-engineered how traits like Spell Reflection change CR. I'm going to spend some time looking over your response and reworking the stat block to see if I can get it closer to what I'm aiming for.

@dave2008 and @aco175 thanks for your replies as well. It's worth mentioning my only plan for this creature is to run it in a couple encounters against my regular party, and we sometimes play a little fast and lose with rules (especially with monster CRs).

My party is six 10th level players, including a large number of spell casters (Wizard, Sorcerer, Tempest Cleric) and a couple melee-based caster types as well (Moon Druid and Hexblade Warlock). Our Barbarian also has a magic weapon, so the weapon damage immunity really only effects the Cleric if he decides to start swinging his mace instead of using spells.

My goal with Spell Reflection was that it only works on spells for which it was the only target (meaning no reflecting fireball etc.), and giving my caster-heavy party something to think about. Maybe stacking Reflection and Magic Resistance is overkill, but as @dave2008 pointed out, without any bonuses to saves, it may still fail most of those as well.

Sharpened Form was copied from Nerzugal's Extended Bestiary, which has it's own version of Obsidian Golem. Perhaps a better way to phrase the desired effect would be:
"If a single creature within deals 20 or more damage to the golem while within 5ft of it in a single turn, a shower of glass erupts dealing etc. etc."
This would clean up things like AoO later in the round or a character attacking in melee then moving away to multi-attack from range. Again, the wording on this is pretty clumsy, but since it's only meant for my own personal use (though others are welcome to use it!) as long as I make it clear to my players how the ability functions, the exact wording doesn't bother me too much.
Debating between making it a small AoE around the golem (which makes more sense narratively) vs. making it deal damage to the target attacking (which is mechanically a little closer to what I want).

Ultimately, I may tweak the stats based on @Quickleaf 's comments, repost the updated stats, and play it a little loose for my group. Since we do milestone leveling, the total XP doesn't matter, so CR is mostly just me trying to make sure I don't stack the odds too heavily against my players. That being said, they've been able to handle most threats I've thrown at them without too much issues, so I'm not against making them sweat a little here or there.

Thank you all again for your input!


I assume this golem will not be alone then? 6 lvl 10 PCs would make short work of this monsters if it is by itself.

Sharpened Form was copied from Nerzugal's Extended Bestiary, which has it's own version of Obsidian Golem. Perhaps a better way to phrase the desired effect would be:
"If a single creature within deals 20 or more damage to the golem while within 5ft of it in a single turn, a shower of glass erupts dealing etc. etc."
This wording seems a bit odd to me, but if you understand it - then it is all good. However, personally, I think @aco175 suggestion is simpler and probably better. However, if you are looking for the narrative of when it takes a lot of damage the shards fly off, then maybe it doesn't work for you. If that is the case, how about:

Sharpened Form. When a creature within 5ft of the obsidian golem makes a critical hit against the golem, a shower of glass erupts dealing 8 (2d6) slashing damage to the attacker. Additionally, any creature adjacent to the attacker must make a DC 15 Dexterity saving throw or take the same damage.

Trit One-Ear

Yeah, I'm thinking 2-3 of these things plus a trap/hazard room (titling floor with lava running to the low point/the area with the most creatures).

Simpler probably is better... especially since I'll also be managing the lava hazard. I'll toy with the two ideas, you may have well convinced me to simplify it to what @aco175 suggested. The desire is for there to be different penalties for how players engage it, as I have 3 players who can both attack with spells at range or melee it. As long as there's a trait that effects each, I'm happy.


Love the tilting lava floor. I think that will make for a really fun encounter with these guys! I agree with @dave2008 and @aco175 that it could play easier than the numbers I worked up for it. In my experience, this is because golem fights are more party composition dependent than other fights, and your obsidian golem especially so (auto-damage spells like magic missile or cloud of daggers ftw). If you have the right abilities (e.g. Pact warlock, magic weapon and similar spells, ways to pierce or circumvent Magic Resistance like bane, monk laying down Stunning Fist, etc) and use a modicum of strategy, a party can tear through a golem. However, face one without magic/adamantine weapons and without those capabilities in your party, and it becomes much more challenging.

Anyhow, I'd been thinking that the golem had a roughly 50/50 chance of making its save, but I was assuming:
  • It was facing 5th level PCs with a typical save DC 14.
  • The PCs could field two offensive spells per round. One spell would get through its magic resistance, the other spell it resists (and can use Spell Reflection on).
  • It would have a 80% chance of saving vs. Constitution, 58% chance of saving vs. Wisdom, or 51% chance of saving vs. Dexterity. And the PCs would usually target Dexterity.

However, if you have 10th level PCs, the typical save DC for a 10th level PC = 8 (base) + prof (4) + ability mod (let's say 4) = DC 16. In that case, the golem would have a 70% chance of saving vs. Constitution, 44% chance of saving vs. Wisdom, or 38% chance of saving vs. Dexterity. So about one-third of Dex spells might get through.

The more offensive casting available to a party (at the exclusion of weapon ability), the higher the chances for its Spell Reflection to get triggered.

The stricter the conditions you put on Spell Reflection (i.e. deviating from the spectator such that area effects aren't reflected), the lower the chances for Spell Reflection to get triggered.