Underdark Rift

The instruction to roll a die and the effect that occurs because of the result are all part of the same ability. Players do not get the chance to respond to the ability after knowing the result of the roll.

Dice are identified by the number of faces each one has. For example, a d20 is a twenty-sided die.

An effect that says “choose a target, then roll a d20” or similar still uses the normal process of putting an ability on the stack and resolving it. Choosing targets is part of putting the ability on the stack and rolling the d20 happens later, as the ability resolves.