Here's a snapshot from TCGplayer, capturing the three most valuable out the gate: As you can see, one can potentially open a $400+ card from a collector booster if they're lucky enough
You can try out a new MTG cube format to get a new feeling from the game
While a 3/2 for four mana isnt great, the ability to counter a wide range of effects (spells, activated abilities and triggered abilities) or destroy a creature or planeswalker when Ertai enters makes this card an amazing Swiss Army knife that can answer a number of kill-on-sight threats, often in a surprising way, as the fact that this card counters triggered abilities can really stymy a foes game plan in unexpected ways
Undead Augur Undead Augurs in that same category as the 3-drop card advantage creatures, but its a 2-drop, and is actually relevant for a certain black devotion wincon
There are six primary ranks for each format: Bronze, Silver, Gold, Platinum, Diamond, and Mythic
There are nuances White Plume Adventurer is the cheapest, Caves of Chaos Adventurer performs well in cast-from-exile decks, etc