For Mirror Box, that rule is the legendary rule that says you're only allowed one copy of a legendary creature card on your battlefield at the same time
The 10 best Dragons in Commander We could write an honorable mentions list the size of a full Commander decklist here, so well just limit ourselves to one
The more recent menace, Nadu, Winged Wisdom, contested this
Realms and Relics Box Toppers This set has a selection of 30 lands and artifacts that are all desired reprints, going from important lands like Urborg, Tomb of Yawgmoth, Karakas, and Cavern of Souls to staple artifacts like The Great Henge, Shadowspear, and Ensnaring Bridge
It cant be the target of Tenacious Tomeseekers triggered ability (return target instant or sorcery card from your graveyard to your hand)
He is grinding and streaming Magic Online full time, and we are happy to have him as one of our authors on the Three for One Trading Blog team