There are 114 creatures in Standard with abilities that trigger when they enter the battlefield. I’m guessing there’s going to be a way to abuse this:
Making him indestructible is of course nice, but the true power of the card lives with the apparent cost of the ability. Here’s selection of creatures you might want to look at:
I left out things like [scryfall]Scourge of Fleets[/scryfall], [scryfall]Fanatic of Mogis[/scryfall] and [scryfall]Gray Merchant of Asphodel[/scryfall] because they probably wouldn’t fit into a heavily green deck.
Most of these need quite a slow format to work, but they do bring a sense of inevitablity, just like [scryfall]Whip of Erebos[/scryfall] in the current Abzan and Sultai Whip decks. Using Sabertooth in a similar role will be awkward and slow, but there’s plenty of opportunities here.
These decks already play plenty of the creatures mentioned above, but of course, since its me, I’m starting with a monogreen build:
Using Matt Sperling’s deck from GP LA as a sort of template:
4 Elvish Mystic
4 Whisperer of the Wilds
4 Voyaging Satyr
4 Courser of Kruphix
1 Nylea, God of the Hunt
3 Temur Sabertooth
3 Hornet Queen
4 Polukranos, the World Eater
3 Genesis Hydra
3 Nessian Game Warden
1 Bow of Nylea
2 Setessan Tactics
4 Nykthos, Shrine to Nyx
4 Windswept Heath
4 Wooded Foothills
I exchanged [scryfall]Sylvan Caryatid[/scryfall] for [scryfall]Whisperer of the Wilds[/scryfall], because I felt the potential one more mana is more important than hexproof or the extra toughness. I’m not sure though. Might not work out as hoped.
There’s some synergy with [scryfall]Temur Sabertooth[/scryfall] and [scryfall]Setessan Tactics[/scryfall] as you can pick a fight with no risk to the cat.
The [scryfall]Bow of Nylea[/scryfall] is highly speculative. If [scryfall]Hornet Queen[/scryfall] and fast red decks stay popular, its going to be pretty good. Otherwise… not so much. It does give a pretty good source of devotion, though.
Since the Abzan and Sultai decks already have a pretty good collection of good cards and key four drops, its hard to find room for the Sabertooth there. On the other hand, its not really a four drop. Mosty you want to play it as a six drop, so it might have a place in a slower version.
Also, it could be an excellent sideboard card against certain decks. It can save another creature and itself from a sweeper, or just make spot removal extremely awkward. It depends on whether the tempo loss is worth it or not.