Can't explain that

Until end of turn, whenever a player taps an Island for mana, that player adds an additional .

Imprint — , : You may exile an instant or sorcery card with mana value X from your hand. At the beginning of your upkeep, you may copy a card exiled with this artifact. If you do, you may cast the copy without paying its mana cost.

Enchant player At the beginning of enchanted player's first upkeep each turn, that player gets an additional upkeep step after this step.