What does Addendum do in MTG?

Addendum is an official Magic: The Gathering keyword. The ranked cards above show how it works in practice.

What is the best Addendum card?

By popularity, Unbreakable Formation is among the most-played Addendum cards — see the full ranked list above.

Addendum is a Magic: The Gathering keyword. Below are the best Addendum cards of all time, ranked by popularity.

What does Addendum do in MTG?: Addendum is an official Magic: The Gathering keyword. The ranked cards above show how it works in practice.
What is the best Addendum card?: By popularity, Unbreakable Formation is among the most-played Addendum cards — see the full ranked list above.