The most likely place for this combo (in fact the only place where a 10 mana combo is viable) is Commander games, where the combo could help you dig for a key card in your deck, whatever win condition or answer you need
As far as new cards go, Pioneer is fairly stable, with very few new cards each year becoming relevant
Against fair decks this is well worth it but against a combo deck where it is just a pure race this massive momentum swing can be too late
When the last is removed, you may cast it without paying its mana cost.) Illustrated by Randy Gallegos Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Not Legal Modern Legal Brawl Not Legal Legacy Legal Comp
All planeswalkers are legendary, so most legends matter cards work with them, and they also turn on legendary instants and sorceries like Yawgmoth's Vile Offering
As a reminder, Zimone, Infinite Analyst, also reduces the cost of X spells for each counter on her, meaning if she were to have 14 counters, you can declare an X cost of 14 for X spells without having to pay anything other than the remaining colored mana cost
