Seven Dwarves

This creature gets +1/+1 for each other creature named Seven Dwarves you control.
A deck can have up to seven cards named Seven Dwarves.

"Till I hit that lode and find great treasure."
"Away swing away, strike the ore true."

Secret Lair Drop

"I used to hunt gems, till I got too rich."
"Away swing away, strike the ore true."

"Then I lost it all and wound up in a ditch."
"Away swing away, strike the ore true."

"The gleam of rubies and my brothers and sisters by my side . . . what more could I want?"
—Brognold the Third

Throne of Eldraine

Because damage remains marked on a creature until the damage is removed as the turn ends, nonlethal damage dealt to one Seven Dwarves may become lethal if another Seven Dwarves you control leaves the battlefield during that turn.

If you're fortunate enough to open or draft eight or more Seven Dwarves during a Limited event, you can include only seven of them in your deck. The rest remain in your sideboard.

The last ability of Seven Dwarves lets you ignore the "four-of" rule. It doesn't let you ignore format legality. For example, during a Throne of Eldraine Limited event, you can't add Seven Dwarves from your personal collection, no matter how happy they would be.