Have you ever seen a real playtest card up close
I can highly recommend you try to do this at least once (and yes, this works, since them paying 50 life is the cost to activate the ability, they will still lose the life even if you counter the ability
Beyond that, green also offers you ways to add extra lands to the board, even at instant speed
In the spirit of saving you some time, heres my very first article featuring a deck tech for Commanders Herald
Consider adding cheap staple cards like Kodama's Reach, Cultivate, or something like Emergent Sequence, Greenseeker (it also discards you a creature that you can pick up with meren at the end of turn), Primal Growth (good sac outlet too), Dawntreader Elk, Deathsprout, Diligent Farmhand, Rampant Growth, and notable Yavimaya Elder
Top 5 Deck Building Tips With all of these different directions you can take your deck, it can become a daunting task to hone in on something concrete