This consists of playing down cards, using an ability from one of your cards, moving a character to a location, or taking an action with a character who has been in play since the start of your turn like questing, or challenging your opponent
The two colors it protects from are fairly common, but the real attraction is the triggered ability
These sheets are often thematic, and March of the Machine's is no different
Unlike the cards in the main set, Through the Ages cards do not become legal in Magic's Standard format (though they still are if the existing card was already legal there, of course), essentially just making them alternate art versions of those cards
Its actually quite frustrating to actually try and build a Standard tribal deck