Spirit of the Labyrinth can seriously choke blue and green decks, Aven Mindcensor can turn a fetchland into a Wasteland, and Imposing Sovereign can shut down any creatures with haste
If X is 10 or more, instead shuffle your graveyard into your library, draw X cards, untap up to five lands, and you have no maximum hand size for the rest of the game
These will either fit into one of the four categories (aggro, midrange, control, combo) or combine a mix of them
If it happens on turn three, that will cost them several cards, but they can usually get those cards back
Theres a ton of applications for this: you can elk your own cards once youre done with their effects, you can elk the Food token he makes, and best of all, you can elk your opponents big creatures and artifacts essentially making Oko a persistent answer to that your opponent will need to play around