When two characters are facing off you roll initiatives to determine who goes first.
whoever rolls higher goes first but declares their actions last. this allows them to see what other characters are doing and act accordingly. basically if you win the roll your character sees it coming and can preempt the other characters.
In order to determine initiatives you take you dexterity score and add it to your wits score then take that total and roll a single 10 sided die. the total of that die is adds to your wits + dex.
for example if you wits are 3 and your dex is 4 you would roll a die and whatever the total you would add it to 7 (wits 3 + dex 4)
In the dice channel you achieve this by typing:
!inits (wits) (dex)
in the previous example the roll would look like this:
!inits 3 4
and the Bot Misty will read you your score.