One of Rotting Chaos

When One of Rotting Chaos enters the battlefield, search your library for a forest card, reveal it, and put it onto the battlefield tapped, then shuffle your library. If you control a swamp, instead search your library for two forest cards and reveal them. Put one of them onto the battlefield tapped and the other into your hand. Shuffle your library afterwards.
Beware the plague, it's contagious!