Clay Golem

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.

While playing Planechase, rolling the planar die will cause any ability that triggers whenever a player rolls one or more dice to trigger. However, any effect that refers to a numerical result will ignore the rolling of the planar die.

An ability that tells you to roll a die will also specify what to do with the result of that roll. Most often, this is in the form of a “results table” in the card text.