Armor/Armour class question

[Jay]

I'm playing a game with randarts and some items have come up with high AC bonuses. For example, I've got a +43 cloak, a +37 sling, and the arkenstone has a +20 bonus. My current AC before blessing is 280 but I can get it up over 300 if I swap a few items.

So, my question: Is there maximum useful AC? I know with speed, you hit a point of diminishing returns (+30 hasted is great, +50 is overkill). Can I reach a point where my armo(u)r is so good that I will only rarely be hit in melee?

Thanks!

[Magnate]

I'm playing a game with randarts and some items have come up with high AC bonuses. For example, I've got a +43 cloak, a +37 sling, and the arkenstone has a +20 bonus. My current AC before blessing is 280 but I can get it up over 300 if I swap a few items.

So, my question: Is there maximum useful AC? I know with speed, you hit a point of diminishing returns (+30 hasted is great, +50 is overkill). Can I reach a point where my armo(u)r is so good that I will only rarely be hit in melee?

Thanks!

The chance of being hit in melee depends also on both the monster level and its attack power, so it's not straightforward. Against Morgoth's shatter attacks an AC of 540 guarantees that you will only get hit the minimum 12% of the time - but the maximum useful AC is far lower than that for most of the game.

AC also absorbs physical damage. For this purpose the maximum useful AC is 240, which is achievable but not common.

[Jay]

Ah, great, thanks for the info. 540 (!) is out of range, but I should have no problem keeping things over 240 without going into contortions.

[OOD Town drunk]

The chance of being hit in melee depends also on both the monster level and its attack power, so it's not straightforward. Against Morgoth's shatter attacks an AC of 540 guarantees that you will only get hit the minimum 12% of the time - but the maximum useful AC is far lower than that for most of the game.

AC also absorbs physical damage. For this purpose the maximum useful AC is 240, which is achievable but not common.

Do you know the specific values involved in the AC damage absorption and/or the AC evasion equations? Or at least the percentage of damage 240 AC would absorb? It is hard to make adequately informed decisions regarding competing pieces of contrasting equipment when I can't figure the actual difference between 40 AC and +3 DEX, you know?

[Magnate]

Do you know the specific values involved in the AC damage absorption and/or the AC evasion equations? Or at least the percentage of damage 240 AC would absorb? It is hard to make adequately informed decisions regarding competing pieces of contrasting equipment when I can't figure the actual difference between 40 AC and +3 DEX, you know?

From memory, 240AC absorbs 60% of physical damage (AC/400). I think the to-hit equation is something like if randint(mon_lev * 3) + X > AC (where X is a bonus specific to the attack type) but I'm not certain about that either. Both are in the source (I think the file is now called mon-atk.c, the one dealing with monster melee). There is a min 12% chance to hit and 5% chance to miss.