# Target 20 as new to-hit mechanic?

#### Walker N. Waistz

##### First Post
After this thread linked to Mike Mearls's old blog, I poked around some more and looked at when he was running AD&D (not his more recent 1981 D&D rules game). He noted he was using some house rules, including "Delta's Target 20", which I checked out.

Basically, it is "Roll d20 + attack bonus + AC". You always hit on a 20 or higher, or miss on a 19 or lower. (This is based on the era when lower AC was better). Attack bonus was defined as level for a fighter, 2/3 level for a cleric, 1/2 level for a wizard. Blog entry is here: Delta's D&D Hotspot: What is the Best Combat Algorithm? Mearls even comments on the blog entry and indicates WotC might be receptive to this mechanic.

Anyways, I was just wondering if anyone thought this is the way it might go. I do sort of miss descending ACs, though I am not sure why. But always having the same Difficulty for an attack roll is sort of nicely intuitive.

Someone may have posted this before, in which case I apologize for the redundant post.

#### BobTheNob

##### First Post
Cant say I miss descending AC. Any like of it is purely nostalgic.

That said, I kinda like it more like this
d20 + attack - defence. an 11 or greater is a hit

This allows that
* higher defence is better
* Attack and defence can be on the same scale

Actually very close to the original model in probability, but allows that attack and defence numbers are scaled the same and can be easily compared

#### Herremann the Wise

##### First Post
I'm not a fan of the 20 as a target idea. I prefer the target to be variable and representative of difficulty thus immediately informing me in a minimum amount of space as to the difficulty of a particular task.

Further, I like the idea of an absolute (rather than relative) set of target DCs ala that old 3.x table. DC 0 can always be performed by someone who is unimpeded, while a DC 40 is at the limit of mortal endeavour.
I still remember that DC 43 survival check:
* Track a goblin that passed over hard rocks a week ago, and it snowed yesterday.
** Who could do it: A 20th level ranger who has maxed out his survival skill and has been fighting goblinoids as his favored enemy since 1st level.

Best Regards
Herremann the Wise

#### triqui

##### First Post
I'm not a fan of the 20 as a target idea. I prefer the target to be variable and representative of difficulty thus immediately informing me in a minimum amount of space as to the difficulty of a particular task.

Talking about attack, theres no real diference. And talking about skills, there's not either, if DC are modified to a bonus/malus to the roll.

DC 15 in a normal roll is exactly the same as DC +5 with target 20. DC 25 is the same as DC -5 with target 20.

#### Herremann the Wise

##### First Post
Talking about attack, theres no real diference. And talking about skills, there's not either, if DC are modified to a bonus/malus to the roll.

DC 15 in a normal roll is exactly the same as DC +5 with target 20. DC 25 is the same as DC -5 with target 20.
I understand that mathematically, there is no real difference, but I find it easier to have that modifier baked into the DC rather than forced out to maintain the 20+ equals success thing.

I think the core mechanic of 3e/4e is the best evolution of this and represents the core D&D mechanic distilled into its purest form. Personally, I would like to see the mechanic furthered (and further complicated) by having a double DC; to provide three possible outcomes rather than two. This would allow some truly funky designs to be thrown into the mix, to better model the outcome of a task. But that's just the inner mathematical nerd in me wishing a little too hard I think. Still, with a double DC, you can do some truly awesome things.

Best Regards
Herremann the Wise

#### trancejeremy

Cant say I miss descending AC. Any like of it is purely nostalgic.

I dunno, while it was later abandoned, one of the nicer things was that it basically constrained AC from 10 to -10.

3e suffered (IMHO) from an inflation (explosion, really) in combat numbers - hit points, AC, etc, for both characters and monsters. Was it really needed? Why not stick to a smaller scale, rather than exploding everything to ridiculous numbers...

#### Libramarian

When I was running Basic D&D I used THAC0, because I didn't want to use a DM screen or any tables, I wanted all the rules in my head.

I considered "target 20" but I came up with this which I like better:

Roll d20,
- if 11-20, attacker compares to THAC0, equal or greater = hit.
- if 1-10, defender compares to AC, equal or greater = miss.

Both THAC0 and AC are like saving throws: roll over, something good happens. No mathematical operations required, just 2 comparisons.

Now that I'm running AD&D I use attack tables, because I need a DM screen for rules reference, so I might as well put more tables on there.

#### Serendipity

##### Explorer
Interesting. Not that I have any desire to go back to the "AC runs backwards" era, but it's not something that would stop me from opting into a game as a player.

#### dkyle

##### First Post
Target number 20 seems completely silly to me. I don't see any redeeming value to it at all compared to d20 + bonus, compared to a DC. It's basically replacing a comparison to a variable number, with an addition of a variable number, plus a comparison to a static number. Comparisons are faster than additions, generally, especially since "target 20" requires communicating the DC to the player, whereas "target DC" does not. It's just seems different for the sake of being different.

Descending AC is silly too, but at least there's nostalgia value to it. But any and all mechanic properties of descending AC can be represented using ascending AC, with the benefit of being less counter-intuitive.

#### Jack Daniel

##### dice-universe.blogspot.com
When I run basic D&D, I use an even simpler algorithm:

Roll under (enemy's AC + your Attack Bonus) and you hit. If you roll a one (an "ace"), you crit.

Works like a charm.

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