Magecraft is an ability word, so it carries no rules meaning by itself. It labels a family of triggered abilities that share a pattern. In the examples, each Magecraft ability begins Whenever you cast or copy an instant or sorcery spell and then resolves an effect—creating a Treasure token, drawing a card, gaining 1 life, or granting a creature a leave-the-battlefield replacement and a token-making follow-up.
Because the trigger watches both casting and copying, the ability rewards decks that chain instants and sorceries. A single spell can set off every Magecraft permanent you control, so the ability scales with the number of such permanents and with effects that copy spells. In play, that makes Magecraft a value engine: cheap cantrips and rituals can turn into tokens, cards, life, or other advantages.
