For the Unknown Event cards, your best bet is probably to proxy any that have previously existed, though you might occasionally find a few on the secondary market
The early meta is focused on using Sapphire to control and generate lots of cards quickly with Pawpsickle and Hiram Flaversham, Toymaker, but we may see more Sisu sooner rather than later
Giving your opponents counters works out well in EDH because you can make a friend, and you can even broker a deal to give somebody an Oblivion Stone or something should that seem like the best option
The expansion is set to launch on June 13
It pairs especially well with commanders like Marath, Will of the Wild, since scalable abilities get even stronger every time you use them
We have previously seen it in only collector boosters (planeswalkers in collector's boosters for Bloomburrow ), multiple types in each play/draft booster ( Wilds of Eldraine , and March of the Machine ) as examples, and more