Tamiyo, Field Researcher
Legendary Planeswalker — Tamiyo
+1: Choose up to two target creatures. Until your next turn, whenever either of those creatures deals combat damage, you draw a card.
−2: Tap up to two target nonland permanents. They don't untap during their controller's next untap step.
−7: Draw three cards. You get an emblem with "You may cast spells from your hand without paying their mana costs."
Illustrated by
Bloomburrow Commander#100MythicEnglishLegality
Rulings
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.
You must follow the normal timing permissions and restrictions of each nonland card you cast once you get Tamiyo’s emblem.
If you cast a card “without paying its mana cost,” you can’t pay any alternative costs such as emerge costs. You can pay additional costs such as escalate costs. If the card has mandatory additional costs, you must pay those.
If the card has 
in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.
You may still cast nonland cards by paying their mana costs as normal.
If Tamiyo’s first ability targets two creatures, and both deal combat damage at the same time, the delayed triggered ability triggers twice.