Many WUBRG cards are eminently flavorful, impressively powerful or a combination of both across a wide variety of formats ranging from game-changing creatures to brutally powerful enchantments
Espeon's version from the Pokmon POP Series 5 Cards is particularly breathtaking, featuring gorgeous artwork that perfectly captures the shiny green psychic fox's elegance
All of this is to say that Oko is extremely hard to answer in combat, so it largely requires a spell to deal with it (or, as we see in Throne of Eldraine Standard, you can go way over the top of its threat generation by, for example, making lots of 2/2s with Field of the Dead)
Despite this seemingly strong effect, it hasn't seen much competitive play
You choose whether to cast the exiled card as Power Pack's delayed triggered ability resolves during your next upkeep
A bit disappointing in that regard, but honestly if Lonis didn't have an activated ability at all she'd still be amazing due to the triggered ability