Roll for Defense!?! PCs roll vs Room Target for Defense?




Has anyone tried using the Target/Effort mechanic to develop a “Defense” mechanic instead of using traditional armor? If so, are there any pitfalls to watch out for?

My group is starting a ‘red shirt’ trekkie homebrew where wearing armor doesn’t really fit thematically, but we still need an armor or defensive type mechanic. I’m trying to figure out a simple and fast alternative to a traditional armor rating. I can’t remember the system, but I thought I heard about a d20 system that has players roll against the incoming attack. I liked that idea and wanted to get your input on this mutation I’ve thought up.

Traditional Armor = Base+Loot+10. The DM rolls a d20 and if it meets or beats the PC’s calculated Armor, the player takes damage.

The Defense Mechanic would work differently. A “Defense” score would be calculated using Base + Loot (just like any of the other 6 stats). The DM would announce who the monster is attacking. That PC would roll a d20, adding in their “Defense”, against the Room Target. If their roll + Defense number meets or beats the room target, they avoiding the incoming damage. If they fail, they would take damage.

I am not sure how to calculate damage. Whether it is just a 1d6 + monster attack roll by the DM, or if there is a simple calculation based on the difference between the Room Target and their Defense.

Any Ideas would be welcome. Thanks!

A different different approach to Target Numbers

Good idea! Perhaps integrate saves into this? So instead of rolling DEX + LOOT, replace DEX with an attribute of the appropriate choice and it would be pretty cool! :smiley:


Melee combat could be pretty easily morphed into simple opposed rolls: highest roll (Base + LOOT) wins and deals damage. This more closely reflects the give and take of hand-to-hand combat: combatants are vying for purchase and it’s not always “I swing, you swing, I swing, you swing”. Rather, both are always swinging.

This doesn’t work as well for ranged combat, but that could be a combat roll vs a DEX roll.

You could also nerf your bad guys a bit, so that they’re just not very good at fighting and the lack of armor is offset.


I don’t know if I am reading this right but it seems that the Defense Mechanic would replace the DM’s attack rolls so all the rolling would come from the players except perhaps for damage. Does that sound right?

An opposed roll may be an option as mentioned above. I see using this as taking the room target out of the equation for combat (it could stay in for other actions though). I agree that ranged attacks might be tricky but roll vs DEX may work.

Moving in this direction does start to get away from the core of ICRPG mechanics a bit but perhaps that is not a concern.


This is rich!!! Can’t write up what I want to Yet…but this is sooo rich!!!

First ICRPG preaching, armor is not armor but the abstract of a target number for the bad guys…preaching done cause this is cool. You could call it luck and proceed as normal.
Preaching over.

But this is too rich. Keep calling armor luck, and use it for other mechanics.

Second, I would go a step further. If theme is more important than realistic playability.

When bad guys attack, it attacks with room target number and does damage at the same time. Players all roll their defense and the lowest defender takes the hit. But gets a marker.

Typically the competent members of the crew then dispatch the foe. You decide total number of attacks, but if all players roll over room numbers, that hit misses.

Markers allow redshirt to allow the hit to hit someone else. Be it the NPC crew, or other redshirts.

To balance this, don’t let the PCs accumulate more than 3 markers at a time, and give officers 1~3 underlings of their own.

The main focus of the redshirts should be back room deals and avoiding danger. Loot gives them bonuses fencing contraband and or avoiding duty…away missions are the most dangerous, but in play time should be short and not detailed.

“You are accompanying Lt. Kirrega as he samples all the flora in the giant jungle down below…our instruments can’t penetrate the canopy, we’re sure it’s not dangerous.”

You declare, while taking samples there are 8 attacks…and a kidnapping. You roll damage 8 times they roll to avoid being hit…lowest takes it, then based on surviving crew, you roll effort however many times it takes to get to 10. They avoid the effort as best as possible to have someone else get kidnapped.

Away mission give no loot, no rewards other than markers. Markers can be used along with other things to gain influence to ultimately get transferred off of any ship. But they can’t be too competent…
Have another mechanic of temporary, consumable bonuses.

They want influence and no notoriety. Notoriety, usually goes with influence, but it can be decoupled by getting in some trouble or blackmailing others to take the credit in the reports.

Cause the only thing worse than being a redshirt for life expectancies is a just promoted favorite of the Sr. Officers.

Goal of a Red Shirt should be to get back to civilization and be transferred planet side.


I don’t roll enemy attacks as dm, I have players roll dex to dodge. If they have a shield then they can roll strength to block. The DC is the room DC. A dodged or blocked attack does not hit. As dm I roll monster damage in the open and Armor absorbs damage.

It actually brings a different energy to the table I love it. Armor absorbing damage is cool when playing games like Icrpg with scaled down HP. It doesn’t take much time because players can calculate the simple math as you move on to your next move.


I keep seeing people talk about not wanting to “stray from Icrpg core mechanics”. The Runehammer videos to me communicate that you should do it your way. Stray away and make no book law, including Icrpg. Do what’s cool for your table.

Sorry I just had to throw this out there. What turned me onto runehammer in the first place was being shown that you can take from your favorite rpgs and make your game your own. I’d hate to see people lose that spirit because hankerins books do it one way.

I get that this is a forum for Icrpg but it seems more like a community of DIY RPGers more than anything. Don’t lose that.


This screams “Durability” checks for armor and shields. I like this.

I commented on another thread about ideas for durability. The nutshell is that instead of using a Usage Die dice chain (d20->d12->d10->etc) everything gets a durability score of up to 5. Roll on d6 and an equal or above roll would decrease durability until broken. If d6 was too limited, you could increase the durability to a 7 and roll on d8. But I think if you keep it to only checking when you roll a nat 1 on the ATTEMPT, the d6 should work fine.


I like that. Could also make toolchecks/effort for repairing armor cool. Always liked the idea of armor breaking.


Exactly! I was thinking about supplies, food, arrow tracking but figured it could extend to armor and shields. I just wasn’t sure how to do it. BOOM!


OK, explaining my Red Shirt concept.

The redshirt PCs discover early on (once they are PCs), that they are disposable. Their goal is to escape notice of the senior officers and somehow never ever be on an away team.

After a short time they discover, coming to the notice of any planet based commander is their only chance to make it to retirement.

Now serving on a polar planet or a strategic planet is not the goal. They want to be on a recreation planet.

They have to figure out how to have an up and coming officer who is not a plot hook for the senior command of the ship owe them big time.

And it has to be an up and coming officer that will command on a Rest and Relaxation destination. Not in command of a ship, that is unless they can become a senior officer on that ship.

The players goal is to coerce, blackmail, or become essential to an officer who will make it to one of these grand places, or make it that an incompetent officer who owes them looks good enough to make it there and is able to choose some of his crew. All while surviving as a RED SHIRT.

Combat is an ordeal to survive, they must use all their brains and luck to make it back, while senior officers and new officers save the day.

New officers who become central to the senior officers are risky, if a whole away team is going to buy the farm, it’s with a new up and coming officer, or an officer who becomes the love interest of a senior officer.

The real game is the getting an officer in the right position to owe you, not you saving the day.

What shady deals, what other officers need to be badly wounded, for your officer to get noticed by high command, while not being a plot point for the senior officers???

This is a game of meta gaming. Not being heroic. And not getting tossed in the looney bin while you have discovered that reality has a pattern, and that pattern kills RED SHIRTS.


I like this! Less rolling as a DM is a good thing in my opinion.

I hope that my comment about moving away from ICRP core mechanics was seen as a negative thing, this was not my intention at all. I am totally down for hacking and modifying and simply making things work better for a player’s particular needs! I also dig that this is encouraged from the get go and that there is so much DIY here on the forums so by all means keep up the creative spirit!

I was just speaking from first hand experience that it is easy to get sucked down the rabbit hole once you start changing rules where at some point you may look at what you have designed and realized you have an entirely different game (this is not at all a bad thing, just something to take note of). I have been amazed with rpg design that a simple change can often lead to a snowball effect where you have to consider a lot more than you thought you might when you first started. Of course, I tend to maybe think things through a bit too much at times!

Great ideas here guys! I really like a lot of these concepts and look forward to trying some of this stuff out once I get some more play time under my belt.


This sounds highly entertaining! I’d do it.


I do something similar with guns. Rather than track ammo on a per round basis, guns are assigned a usage die. The size of the die varies; a Glock 17 Ud10, a Mossberg shotgun Ud4. On a 1 or 2, the item is depleted. It represents that you are most likely firing multiple shots to hit the bad guy.


I’m thinking of shelving dynamic spell/super science for this. I think I’ll get more chuckles out of it.
But I’m changing a lot to fit more genres, and follow an NPC or Mook theme, this can simply be the sci-fi version.
Likely nothing will come of it, but I might run something based on this at the end of November AZ ICRPG retreat.


I love DELUSIONS’ answers on this…really cool.


I wanted to add to this that I had a player tonight roll a natural 20 on a dodge so I allowed her to have a counter attack. She killed the enemy. It was totally awesome. Just another cool idea - a defensive crit.


Out of curiosity how do you use armour reduction?


Couple of approaches.
Assuming the player rolls some save vs getting hit and missed the target number.

You can treat the armor as “threshold armor” where one has to roll damage over the armor to actually do damage.

Threshold armor = 5

5 damage or less does 0 HPs 6 or more does damage -threshold.

So 8 damage vs 5 armor does 3 hp of damage.

Or you can say each point of armor = 1d6…

When you take damage, say 10…you say I’ll use 2 point of armor to negate that. And you roll 2 D6. And your total armor is reduced by 2… when it gets to 0 it’s destroyed beyond repair.

So I have 3 armor…I get hit for 8. I say I’ll use 2 armor and roll 5 total, I take 3 hit points and have 1 armor left.

And you can combine the 2. Threshold armor, and use points from it to negate more damage, but it is less of a threshold.

I have 10 armor, I get hit for 19 damage…I elect to use 3 armor points and roll 3d6 coming to 8. So total my armor stops 18 points of damage, but I take 1 hp of damage and my armor is now 7 until I repair it.

And you can make armor dice d4 or d10 or d35s (if you have any). But it’s a mechanic, that is very flexible and can fit in a lot of ways. Kind of up to you!


I like to keep it simple and have 3 types of armor. Light armor absorbs 1 physical damage, medium armor absorbs 3, heavy armor absorbs 5.