Tamiyo, Field Researcher

Tamiyo’s first ability can target creatures you don’t control. You’ll draw a card, not their controller, if they deal combat damage.

Tamiyo’s first ability sets up a delayed triggered ability that triggers even if Tamiyo has left the battlefield before those creatures deal combat damage.

If Tamiyo’s first ability targets two creatures, and both deal combat damage at the same time, the delayed triggered ability triggers twice.

If you cast a spell “without paying its mana cost,” you can’t choose to cast it for any alternative costs. You can, however, pay additional costs. If the spell has any mandatory additional costs, those must be paid to cast the spell.

If a spell has {X} in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.