Whenever Radagast or another nontoken creature you control enters, look at the top X cards of your library, where X is that creature's mana value. You may reveal a creature card that doesn't share a creature type with a creature you control from among those cards and put it into your hand. Put the rest on the bottom of your library in a random order.
If the top X cards of your library don't contain a creature card that doesn't share a creature type with a creature you control, you won't get to put a card into your hand. Apologies to Mistform Ultimus fans everywhere.
2023-06-16 • wotc
If a token copy of Radagast the Brown enters the battlefield, its own ability will trigger.