Abstruse Archaic

Abstruse Archaic's ability targets an ability that is on the stack and creates another instance of that ability on the stack. It doesn't cause any object to gain an ability.

Triggered abilities use the word "when," "whenever," or "at." They're often written as "[Trigger condition], [effect]." Some keyword abilities are triggered abilities and will have "when," "whenever," or "at the beginning of" in their reminder text.

Any choices made when the ability resolves won't have been made yet when it's copied. Any such choices will be made separately when the copy resolves. If a triggered ability asks you to pay a cost, you pay that cost for the copy separately.