User:Yodaj007/Sandbox

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[edit] Definitions

  • a: The target AC
  • r: Roll required to confirm critical hit (low end of weapon critical range)
  • b: Bonus damage
  • m: Critical multiplier
  • h: Bonus to hit, including base attack bonus and all applicable modifiers
  • p: Amount of power attack taken from h

[edit] Chance of hitting

The roll required to hit is the AC of the target minus the players hit bonus, or \,R=a-h. If R is greater than 20, the chance to hit normally 0%. But, it's still possible to hit on a roll of 20, if the player can hit the AC with an assumed roll of 30. If R is less than 1, then any roll other than a 1 will hit. If the required roll is 19, then two values on the die can hit. If it is 15, then 6 values can hit. This can be expressed as:


\begin{align}
c_{hit} &= \frac{1}{20}
\begin{cases}
0 & \mbox{if } R > 30 \\
1 & \mbox{if } 30 \ge R > 20 \\
21 - R & \mbox{if } 20 \ge R > 1 \\
19 & \mbox{if } 1 \ge R
\end{cases} \\
&= \frac{1}{20}
\begin{cases}
0 & \mbox{if } a - h > 30 \\
1 & \mbox{if } 30 \ge a-h > 20 \\
21 - a+h & \mbox{if } 20 \ge a-h > 1 \\
19 & \mbox{if } 1 \ge a-h
\end{cases}
\end{align}

\,c_{hit} exists on the interval \left [0.0,\,0.95 \right ].

[edit] Chance of a critical hit

In order to get a critical hit, you first have to hit with a die roll greater than or equal to r. To confirm the critical, you just have to hit.


\begin{align}
c_{poss\,crit} &=
\frac{1}{20}
\begin{cases}
0 & \mbox{if } a - h > 30 \\
1 & \mbox{if } 30 \ge a-h > 20 \\
21 - a+h & \mbox{if } 20 \ge a-h \ge r \\
21 - r & \mbox{if } 20 \ge r > a-h \\
\end{cases} \\
c_{conf\,crit} &= c_{hit} \\
c_{crit} &= \left(c_{poss\,crit}\right)\,\left(c_{conf\,crit}\right) \\
c_{crit} &= \left( 
\frac{1}{20}
\begin{cases}
0 & \mbox{if } a - h > 30 \\
1 & \mbox{if } 30 \ge a-h > 20 \\
21 - a+h & \mbox{if } 20 \ge a-h \ge r \\
21 - r & \mbox{if } 20 \ge r > a-h \\
\end{cases}
\right) \left(c_{hit}\right)
\end{align}

[edit] Damage

The expected damage from hitting is defined as d_{hit} = b\,c_{hit}.

The expected damage from critting is defined as d_{crit} = b\,m\,c_{crit}.

The expected total damage from an attack is defined as:


\begin{align}
d_t &= d_h + d_c \\
&= b\,c_{hit} + b\,m\,c_{crit} \\
\end{align}