Combat

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This is the basic combat flow from Ultima Online. We are following it and added some more mechanics that were not as well known.

  1. Determine the next swing's speed of attack.
  2. Determine % chance to hit.
  3. Randomly determine base damage, within weapon's damage range.
  4. Damage Bonuses
  5. Double all spell damage against non-players.
  6. Check for magical defenses. (Reactive Armor, for example).
  7. Modify for chance to block an attack with the damage absorbed by the shield, if relevant.
  8. Determine hit location.
  9. Modify for damage absorbed by the armor slot hit.
  10. Halve all remaining damage.
  11. Apply final damage.


1. Attack Speed[edit | edit source]

   Attack Speed = 15,000 / ( [Stamina + 100] x Base weapon speed )

This is a widely accepted formula among UO freeshards and can be found on the stratics[1] archive pages. Not much guesswork here.

You can find all of the base speeds in the weapons page.

The values displayed below indicate the delay, in seconds, between strikes (swings of your weapon). The lower the number, the faster the rate of attack. If your stamina drops during battle, so will your attack speed. Note that the minimum swing speed globally is 1.2 seconds.

Speed/Stam 5 25 50 75 100
20 7.5 6.0 4.9 4.2 3.7
30 4.8 3.9 3.3 3.0 2.4
35 4.0 3.4 2.9 2.4 2.1
40 3.6 3.0 2.6 2.1 1.9
45 3.1 2.7 2.3 2.0 1.7
50 2.8 2.4 2.0 1.6 1.5
55 2.6 2.3 1.8 1.5 1.3
60 2.4 2.0 1.6 1.5 1.2
70 2.1 1.6 1.5 1.2 1.2
80 1.8 1.5 1.2 1.2 1.2

2. Chance To Hit[edit | edit source]

   Initial 5 % chance to miss then:
   Hit Chance = ( Attacker's Weapon Ability + 50 ) / ( [Defender's Weapon Ability + 50] x 1.6 )

This is our first deviation from the most common UO knowledge. It has been mentioned a few times[2]. It also feels like the better mechanic. You never have 100% to hit.

Passed this initial check, the regular accepted stratics[3] formula applies. Here is a table of possible hit chances for reference.

Attacker/Defender 5 25 50 75 100
5 62% 46% 34% 28% 23%
25 85% 62% 47% 38% 31%
50 113% 83% 62% 50% 42%
75 142% 104% 78% 62% 52%
100 170% 125% 94% 75% 62%

3. Base Damage[edit | edit source]

This is a pure dice roll. Look at the damage info in the weapons page. Let's take the Katana as an example.

   Katana Damage : 3d8+2 (5-26)

This means it will roll 3 dices with 8 faces each and add 2 to the result, which gives a range of 5 to 26 base damage.

If you are using a mace this is when the damage to stamina will be decided. From what we could find the stratics[4] data that says 3 to 5 stamina damage is dealt by maces when hit seems right. We need a correct formula for it and couldn't find anything with substantial evidence so we went with this:

   Damage Ratio = ( ( Base Damage - Min Damage  ) / ( Max Damage - Min Damage ) ) * 100
   Damage Ratio < 40 = 3 Stamina Damage
   40 < Damage Ratio < 80 = 4 Stamina Damage
   Damage Ratio > 80 = 5 Stamina Damage

The 3 ratio check numbers are very much subject to change but it made sense that the chance for high stamina damage would get lower. You need to score a hit on the 80% upper range of the weapon to get a 5 stamina drain.

4. Damage Bonuses[edit | edit source]

a. Tactics Bonus[edit | edit source]

   Tactics Modified Damage = ( Base Damage / 100 ) x ( Tactics + 50 )

Another widely accepted formula from stratics[5].

Let's use our Katana example from earlier and say the base damage rolled as 22:

  • 20% tactics, ( 22 / 100 ) x ( 20 + 50 ) = 15.4
  • 50% tactics, ( 22 / 100 ) x ( 50 + 50 ) = 22
  • 100% tactics, ( 22 / 100 ) x ( 100 + 50 ) = 33

As you can see low tactics will actually be a penalty to your damage. For reference a chart of the damage scaling from tactics.

Tactics % of Base Damage Dealt
10 60%
20 70%
30 80%
40 90%
50 100%
60 110%
70 120%
80 130%
90 140%
100 150%

b. Strength Bonus[edit | edit source]

   Strength Bonus = ( Base Damage / 100 ) x ( Strength / 5 ) 

Strength is an additive bonus, unlike tactics which is multiplicative one. It is a bonus that will be added onto the final formula. We made the decision to base it off the base damage and not the tactics modified damage as it made the most sense. Once more this is the accepted stratics[6] formula.

Let's get back to our Katana example and assume we have 100 STR, our Strength bonus would be ( 22 / 100 ) x ( 100 / 5) = 4.4

Reference chart:

Strength % Bonus to Damage
10 2%
20 4%
30 6%
40 8%
50 10%
60 12%
70 14%
80 16%
90 18%
100 20%

c. Anatomy Bonus[edit | edit source]

   Anatomy Bonus = ( Base Damage / 100 ) x ( Anatomy / 5 ) 

Anatomy bonus works exactly like the Strength one[7]. Same numbers, same way of applying.

So again out test Katana would give us a 4.4 damage bonus at 100 Anatomy.

7. Shield Blocking[edit | edit source]

   % Chance of Blocking = Parrying Skill / 2
   Damage Blocked = AR of Shield for ranged attacks, ( AR of Shield / 2 ) for melee attacks.

A shield will be twice more effective against arrows and bolts and can be used to it's full potential[8]. A GM in Parrying will have a 50% chance to apply damage reduction to all physical attacks.

8. Hit Location[edit | edit source]

   Head : 21%
   Chest : 51%
   Legs : 28%

This is accepted stratics data[9]. Since we don't have all 5 parts we added head and gorget, chest and hands, legs and arms.

9. Armor Reduction[edit | edit source]

  Damage Absorbed = Random value between 1/2 AR to full AR of Hit Location's piece of armor.

As you can see all the AR that will matter is the one from the armor[10] piece that gets hit. Wearing a weaker part can be a gamble!

A mace will also reduce the durability of the armor slot it hits on top of regular wear and tear the slot will receive[11].

  Durability Loss From Mace = ( Damage Absorbed / 2 ) capped at 7

10. Final Damage[edit | edit source]

   Final Damage = ( Tactics Modified Damage + Strength Bonus + Anatomy Bonus - Shield Damage Blocked - Armor Damage Blocked ) / 2

The damage to stamina will depend on the Final Damage, anything over 60 will damage 40% of the target's stamina, and the lower part of the range is 0% at 5 damage.


Let's close with our initial Katana hit at 22, with GM tactics, 100 STR, GM Anat, blocked by a 32 AR shield and a 30 AR armor slot that had it's worse reduction roll at 15.

( 33 + 4.4 + 4.4 - 16 - 15 ) / 2 = 5.4

This shows the effectiveness of armor and shields, same blow on a naked target:

( 33 + 4.4 + 4.4 - 0 - 0 ) / 2 = 20.9