On a successful attack, roll damage. Damage is calculated from the damage roll listed in the attack's description with the format "xdy+[modifier]" (e.g., for a spell that inflicts "1d8+2" damage, you roll an eight-sided and add 2 to the result; the damage dealt is equal to the total).
Any time an effect says to deal damage using your Spellcast trait, you roll a number of dice equal to your Spellcast trait.
Note: If your Spellcast trait is +0 or lower, you don't roll anything.
For weapons, the number of damage dice you roll is equal to your Proficiency. Note that your Proficiency multiplies the number of dice you roll, but doesn't affect the modifier. For example, a PC with Proficiency 2 and wielding a weapon with a damage rating of "d8+2" deals damage equal to "2d8+2" on a successful attack.
Successful unarmed attacks inflict [Proficiency]d4 damage.