This is an event by Wizards of the Coast to help stores as the world starts to reopen from the COVID-19 pandemic. There are a couple promotional cards available for the event, with different ways to earn each:

Reliquary Tower: Available with any Magic: the Gathering purchase other than a booster box.

• Mechagodzilla (Hangarback Walker): Available as a Buy-A-Box promo for purchasing ANY in stock booster box
• We will have plenty of booster boxes in stock to choose from, including Mystery Boosters!
• Everyone who enters the store during the day will also receive a ticket (no purchase necessary, simply visit the store), and at 7pm we'll draw three tickets from the pool and each of these three customers will have the opportunity to purchase an extremely limited Secret Lair: Ultimate Edition*. 
• *Must be present at time of drawing. The price of this box set will be $275.