Rootbound Terrasaur

Rootbound Terrasaur enters the battlefield tapped.
Whenever Rootbound Terrasaur untaps, you may pay {1}. If you do, search your library for a basic land card, reveal it, put it in your hand, then shuffle your library.
Whenever you play a basic land, put a +1/+1 counter on Rootbound Terrasaur and you gain 2 life.