Flying
Whenever Rith deals combat damage to a player, you may pay {2}{G}. If you do, choose a color, then create a 1/1 green Saproling creature token for each permanent of that color.
You choose whether to pay {2}{G} as Rith's ability resolves. Once you make that choice, no player may take actions until the Saprolings are created (if you paid) and the ability has finished resolving.