For more casual players who simply want to get a good, varied selection of cards that they may or may not use in their decks, Set Boosters are the best option
The tremendous flexibility of this card to take out whatever is posing a problem for you is invaluable, and there is little doubt many will take advantage of it, but this isn't quite the card its predecessors were
In the current metagame of Izzet Murktide, Living End and Wrenn and Six-decks, flexible graveyard hate is almost always useful and even if it is a dead card, it replaces itself
Festering Fungus: Zig-Zagged - Mossfungus inflicts the poison status (when used in one map), but it ultimately can be recovered from
You'll need plenty of wildcards to unlock the top goblin cards on Arena
Plusses can occasionally have removal, particularly on higher-costed planeswalkers, but almost always conditional