When Gamekeeper dies, you may exile it. If you do, reveal cards from the top of your library until you reveal a creature card. Put that card onto the battlefield and put all other cards revealed this way into your graveyard.
{2}{G}, {T}: Reveal any number of green cards in your hand. Target creature gets +X/+X until end of turn, where X is the number of cards revealed this way.
Enchant creature At the beginning of your upkeep, you may put a growth counter on Momentum. Enchanted creature gets +1/+1 for each growth counter on Momentum.
Enchant creature When enchanted creature dies, that creature's controller may search their library for a creature card, put that card onto the battlefield, then shuffle.
Exile target artifact. Search its controller's graveyard, hand, and library for all cards with the same name as that artifact and exile them. Then that player shuffles.
When Yavimaya Elder dies, you may search your library for up to two basic land cards, reveal them, put them into your hand, then shuffle. {2}, Sacrifice Yavimaya Elder: Draw a card.