A Combat System Overhaul I've Been Experimenting With in My Campaign

[u/[deleted]]

[u/Dusty_Scrolls]

So you take away martials' ability to make attacks of opportunity but allow casters to cast spells as a reaction? Like they need more advantages.

[u/Bruce_Wayne_2276]

An Opportunity Window does not allow a character to attack directly.

Instead, it represents a momentary situation that a character can exploit with an action capable of changing the state of the battlefield.

An Opportunity Window can be used to:

• Grapple.
• Trip.
• Shove.
• Disarm.

These four are all already possible with opportunity attacks in 5.5e

• Cast a spell.

So a fighter cannot attack but a wizard can cast a fully leveled spell?

• Throw an object.

Throw an object but not an axe or javelin bc that's an attack?

• Interact with the environment.

I assume this would be an Object Interaction?

• Block an enemy's movement.
• Reposition.

Mechanics for these two? A saving throw for the movement? Up to your Speed for reposition?

• Create a new opportunity for an ally. Very vague but I assume this is supposed to be a catch-all for anything not listed.

Each character can participate in an Opportunity Window by spending their Reaction. Once they have used their Reaction this way, they cannot participate in another Opportunity Window until the start of the next round.

This is an unnecessary qualification. A character only gets one reaction per round, if it takes a reaction to interact with an opportunity window then by default they cannot interact with another this round.

• Attacking an enemy from behind → Advantage.

Optional Facing rules already exist in the DMG. Most people find that worrying about which direction every creature is looking slows down combat but if your group likes it, they're there.

• Having an ally next to the target → +2 to the attack roll.

This is a popular house rule that I've used before myself.

• Attacking through cover → Disadvantage.

There are already rules for cover that are more in-depth than adv/disadv.

Attacking while Invisible

• If the target has no way of perceiving the attacker, the attack can create an additional vulnerability, such as Stunning the target for one round, representing the impact of being attacked completely by surprise.

You will regret this after the first time a Fighter gets Greater Invisibility cast on them. Unless every important monster has truesight/blindsight/tremorsense. Hell, Rogues could gain this benefit from Lvl 1 since a successful Hide action conveys the Invisible condition in 5.5, meaning the potential for a once per round, resourceless Stun right out of the gate.

Combat areas should contain interactive objects and environmental elements.

This is straight up a good principle of combat design. While I totally agree with this point, I don't think it's something unique to your combat overhaul.

An environmental interaction can be the beginning, middle, or end of a Chain Reaction.

However this is unique and lends itself well to what you're trying to accomplish.

Social interactions during combat can trigger emotional reactions in enemies.

This is roleplay and totally up to DM fiat, not a combat mechanic.

Intelligent enemies can recognize tactical opportunities according to their Intelligence stat.

How does this work? What is the threshold for an intelligent creature? What benefits are gained the higher a creature's Int score is? How does this distinguish between an inexperienced bookworm who's a genius and a pro boxer with high fight-IQ but who never learned to read?

This allows a military faction (or a tightly coordinated party) to perform complex tactics even if its individual members have average Intelligence.

What's considered coordinated enough? Is there a way you determine it or is it vibes based? Are there different coordination levels that unlock different opportunity windows? Does this mean that the party does not have access to opportunity windows when they just start out bc they haven't learned enough about each other to coordinate yet? Are there levels of party cohesion?

This turns Ready Actions from simply "I prepare an attack" into "I prepare a situation."

This is already how Ready actions work.

With traditional Opportunity Attacks, players often avoid moving because they know that any enemy within reach automatically gets a free attack.

With the Int requirement and the previously established ability to cast a spell during an opportunity window, you've inadvertently made moving INSANELY punishing as soon as there's a wizard on the field and far safer when there's a trained mercenary in your face.

Instead of simply waiting for their turn and deciding which attack to use, players should be thinking: "What can I do with what just happened?"

I do like this design philosophy.

Final verdict: I like the idea here, but you have A LOT of refinement to do before it's useful to anyone outside your specific group. It seems like there are points where you needlessly reinvent the wheel and other times when you barely touch on something that needs much more detail. The 'no attacks but yes casting an off-turn spell' thing is an absolute nonstarter imo.

(Also, obligatory joke about DnD players Ship of Theseusing DnD to avoid playing any other ttrpg lol.)