You can untap it by putting a -1/-1 counter on it, so pair it with something that offsets the counters or turns it into a non-creature, and youve got infinite green mana
But if you have a base-set card in your card collection, there are a few visual indicators of its worth
We'll be keeping our eyes on Handshake Moxfield, ChannelFireball Ultimate Guard, Moriyama Japan, Sanctum of All, and the three "Heavy Play" teamsWorldly Counsel, Cosmos, and Rampant Growth
The idea of a 100 card set is that this is the middle ground between a full draft set and the smaller offerings such as a Secret Lair
The advantage of Sage is cost but if that is what you are after then Nature's Claim, Degalmor or Naturalize should offer more utility
Depending on your opponents deck doesnt work out that well in constructed since hopefully your deck is all cards that are worth spending all your mana on for the whole game anyway