Overall, Staggering Size could see play in certain decks that prioritize combat damage and trample, but its effectiveness may vary depending on the overall strategy of the deck
A thing I like a lot about these sets is the freedom Wizards has to mix and match different keywords and see how they function together
You can stick with Edgar Markov and build an aggressive Vampire deck by adding more lords, Shared Animosity, and other aggressive tribal-matters cards, or you can go with Licia, Sanguine Tribune and build lifegain combo with Sanguine Bond, Exquisite Blood, Defiant Bloodlord, and the like
I dread to think how much my family has spent on them over the years
you can simply fan them out and scan them in
Any "as [this creature] enters the battlefield" or "[this creature] enters the battlefield with" abilities of the creature will also work