D&D 5E Rules for Sunder

[Enricorix]

SUNDERING ATTACK (Battle Master Maneuver)

When you hit a creature with a weapon attack, you can expend one or more superiority dies and you can attempt to sunder the target’s weapon or shield, if you hit, you add the superiority die to the attack’s damage roll to one item that the target is holding of your choice . If the total of damage is equal to or greater than the weapon damage threshold the weapon is considered sundered. A weapon's damage threshold is the same of a weapon's maximum damage die. (8 for a longsword, 10 for a halberd, 12 for a greatsword). Shields have 8 damage threshold. Oversized (or enlarged) weapons have an extra 4 damage threshold for each size category above the original size. Magic weapons are considered to have an extra damage threshold die per rarity level above common. Magic weapons have resistance to all types of damage and all types of damage from nonmagic weapons.
Special substances. Some special materials as mithral and adamantine have resistance to bludgeoning, piercing and slashing damage from nonmagic weapons. In addition mithral has resitance to weapons that aren’t made of adamantine or mithral. Adamantine has resistance to weapons that aren’t made of adamantine.
Sundered weapon. A sundered weapon (or shield) is still usable but with disadvantage on rolls to attack (or -1 on AC for shields), until get fixed. A sundered magic weapon's (or shield's) magic properties are suppressed until properly repaired. All sundered weapons are treated as if were improvised weapons.
Weapons immunities. As objects weapons are immune to poison and psychic damage. An adamantine weapon or shield is immune to critical hits.







NEW MAGIC PROPERTY:

Shattering Weapon (Minor magic property)
When you make a sunder attempt and you hit a critical score, you deal double damage to the target object even if the object is immune to critical hits.


NEW MAGIC ITEM:

Shatterspike
Weapon (any sword), legendary (requires attunement)
You gain a +3 bonus to attack and damage rolls made with this magic weapon.
Sundering Strike (Requires Attunement). When you attack with shatterspike you gain the benefit of a Sundering Attack as same the Battle Mater's maneuver list once per short rest. You receive a d6 to add to your damage against weapon's damage thresholds. (This dice substitutes the superiority dice from the maneuver). The damage dealt by Shatterspike to any object is doubled. If the wielder scores a critical hit the targeted weapon is automatically sundered, despite of its immunities or the damage taken. If you are a Battle Master and is attuned to Shatterspike, treat as you have sundering attack as one of your maneuvers. If you already have Sundering Attack in your maneuvers list you gain an extra Sundering Attack attempt per sort or long rest.
Using Shatterspike to sunder an unbreakable item is ineffective, but there is a 10% chance of Shatterspike get sundered instead.







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Just to figure out the weapon type's damage die and damage threshold, I made the table as an example:


Weapon Damage Threshold (Resistances)

+1 adamantine longsword	16 (resistance to all types of damage; resistance to bludgeoning, piercing and slashing damage from magic nonmagic weapons that aren’t adamantine)
+1 longsword	16 (resistance to all types of damage; resistance to bludgeoning, piercing and slashing damage from nonmagic weapons)
Adamantine longsword	8 (resistance to bludgeoning, piercing and slashing damage from nonmagic weapons that aren’t adamantine)
+1 Mithral longsword	16 (resistance to all types of damage; resistance to bludgeoning, piercing and slashing damage from nonmagic weapons that aren’t adamantine or mithral)
Mithral longsword	8 (resistance to bludgeoning, piercing and slashing damage from nonmagic weapons that aren’t adamantine or mithral.)
Longsword (Large)(or enlarged)	12
Longsword (Huge)	16
Longsword (Gargantuan)	20

Something to consider:

Wood/bone<stone<iron/steel<mithral<adamantine

Adamantine - resistance to bludgeoning, piercing and slashing damage from nonmagic weapons that aren’t adamantine.
Mithral - resistance to bludgeoning, piercing and slashing damage from nonmagic weapons that aren’t adamantine or mithral
Iron/steel - resistance to bludgeoning, piercing and slashing damage from nonmagic weapons that aren’t adamantine, mithral or iron/steel
Stone - resistance to bludgeoning, piercing and slashing damage from nonmagic weapons that aren’t adamantine, mithral, iron/steel or stone
Wood/bone - resistance to bludgeoning, piercing and slashing damage from nonmagic weapons that aren’t adamantine, mithral, iron/steel, stone or wood/bone

 

[Thyrwyn]

Is this an option for anyone, or only the Battlemaster? If for anyone, it should be workable; if for Battlemaster it should a) Use a Superiority Die (and specify what benefit the die provides), and b) use the same DC as all other Battlemaster Maneuvers. I know it may not intrinsically make sense for a DEX based fighter to use this, but no other Maneuver breaks this mold.

Regardless,

1) you should add a multiplier for creature size. A great sword built for a Giant is going to have more hit points than one built for a medium creature.
2) The AC should be the AC of the creature wielding the weapon, especially if the damage can affect them on a save. This avoids wonky corner cases where it is easier to damage a creature by trying to attack the weapon.
3) Give weapons Damage thresholds or hit point multipliers ( instead of AC ) based on their material.

Just some observations, I hope they help!

 

[Leatherhead]

It's almost simple enough.

I would drop the saving throw (unless somehow you are using a spell that needs one) and add the creatures proficiency bonus to the AC of the item. Then tweak the numbers a bit to keep them smaller at the top end and bigger at the low end. Or alternatively just use the creatures AC (so you do less on the fly math) and beef up the HP on the materials.

A Battlemaster using a power should get some bonus damage.

 

[Enricorix]

Yes it is a Battlemaster manouver...I will change considering all of your points and edit the post later, thanks for the feedback.

 

[Enricorix]

Edition made.

 

[Warmaster Horus]

Sundering seems to me to be more of a byproduct of combat than a deliberate tactic. Sure, shields shatter, but it seems off that targetting a shield, rather than the bearer, would be the goal of someone fighting for their life. Also, what is the chance that the attacker's weapon is harmed in the sundering attempt?

 

[Enricorix]

Sundering seems to me to be more of a byproduct of combat than a deliberate tactic. Sure, shields shatter, but it seems off that targetting a shield, rather than the bearer, would be the goal of someone fighting for their life. Also, what is the chance that the attacker's weapon is harmed in the sundering attempt?

For the simplicity of the rule, no, there is no chance of the attacker's weapon is harmed in the sundering attempt. I'm using the logic of the disarm. Disarm could be seen as a byproduct of a combat as well. Until now there is no rules for damaging magic items for example. Even disintegrate does not harm magic items...

 

[Leatherhead]

Edition made.

That looks much better.
But it seems a very weak combat option, can you still deal damage to the creature while you sunder? Maybe it could be reformated a bit so the normal weapon damage applies to the creature, and the bonus dice (or even total damage) applies to the item. But that said, a battlemaster isn't going to be able to use this move very often and lots of the larger items are just going to ignore it.

OR, wait I just had a flash here, what if the item simply becomes "Sundered?" Still usable but with disadvantage on rolls to attack (or advantage on rolls to hit for shields), until you can get it fixed. Using the HP multiplier just as a save bonus?

 

[Unwise]

It looks OK, but any rule that takes up that much space to explain is not a good 5e rule.

Firstly, I would not let people use Dex for this. It is the domain of the strong guys. The duelist with the rapier might disarm folks, but he is not smashing a shield.

Secondly, I would just say that you succeed at sundering the other item unless it is magical or vastly better in construction.

What is the save DC for? Who or what is rolling against it? If you want a roll against it, then I guess just roll a d20 and add +2/4/6/8 to reflect how well the item is made.

I don't see the point of using HP to dictate a weapons quality. That means a rogue with sneak attack and a dagger is more likely to break something than a brute with a maul. Damage is not that great an indication of raw impact.

 

[Sebkha]

By and large, players do not like having THEIR stuff sundered; there's an entire thread exploring this in detail: http://www.enworld.org/forum/showth...o-Sunder-(Break-Destroy-Steal-the-PC-s-gear-)

I'd suggest being lenient about letting people fix stuff, so that sundering instead becomes a temporary setback and an opportunity for the players to show off with artisan's tool proficiencies, Mending cantrips, and the like. Because Elrond reforging Narsil as Andúril? Totally cool.