So whilst The Ringhart Crest is a card you would never put in your deck on its own, with its restrictions on how you use its mana making it a touch worse than previous variants of this style of card, there is precedent for such a card being worth your time and mana in Standard
Most are expensive (Wave of Indifference), miss some creatures, (Falter) or work on you too (Bedlam)
Kenway bucks the overall trend of the expansion by actually being a very powerful Commander for Vehicle decks and beyond
Sylvan Safekeeper acts as a repeatable source of Hexproof, and is thus one of your strongest options versus midrange decks
#5 Amalia Benavides Aguirre Amalia Benavides Aguirre is a strong card for multiple reasons
On the other side, many green decks are built around Llanowar Elves and Badgermole Cub, using their accelerated mana production to deploy powerful threats ahead of schedule