Tawnos, Urza's Apprentice

If the activated ability's cost contains a choice, such as a creature to sacrifice or a number of counters to remove, the copy uses that same information. You can't pay the cost again, even if you want to.

If the ability is modal (that is, if it says, "Choose one —" or similar), the mode is copied and can't be changed.

The source of the copy is the same as the source of the original ability.

An "artifact source" is a permanent, spell, or card in any zone with the card type "artifact." For example, Tawnos's ability can target a cycling ability you've activated if the discarded card is an artifact card.

Tawnos'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.

If the ability divides damage or distributes counters among a number of targets (for example, the ability of Verdurous Gearhulk), the division and number of targets can't be changed. If you choose new targets, you must choose the same number of targets.