So if you want to open playtest cards, you'll need the convention version of Mystery Boosters
In the run-up to the games official big debut at tabletop convention Gen-Con in August of 1993, the company already had a few groups working on bigger expansions including the set that would eventually evolve into Ice Age
LET 'EM
Since Ayula loads up on +1/+1 counters, you can power her up past what your opponents can handle, all while slapping on a few Mirran swords and hexproof auras to make sure your opponents cant interact with her at all
While theres a lot of synergy here, the cards are mostly strong independently, and the deck is designed to play a fair, interactive game that just happens to be able to gain infinite life with Urza and the Thopter Foundry / Sword of the Meek Combo, but mostly Urza, Oko, and Emry are all amazing standalone cards that require fairly different answers