If both targets are illegal, the ability doesn't resolve.
There are so many decks this works in, and Im excited to try it out
Lomelda had spent four semesters on the waitlist for Kasminas Advanced Polymorphological Theory seminar
As long as you aren't running a Stax deck that is actively limiting your opponents from casting multiple spells per turn with cards like Winter Orb I think you'll get enough value out of Mangara to justify its slot
Thereafter it becomes your opponents turn, and your opponent will likewise draw a card, use any of its planeswalker abilities, make a match, and have its creatures attack
However, WotC has mentioned that these packs will prioritize the new-to-digital Magic cards, awarding rares from the Standard set only once all Alchemy-specific rares have been collected