This has been widely discussed and for a reason. There’s a couple of very good tools. This is my take.
One way to design a deck is to go back from how you want the turn you win to go. In this case, we want to cast [scryfall]Aspect of Hydra[/scryfall] and push enough damage through that way. So, we begin with a set of those. Then, we need have enough pips to get the damage we want. So, our curve should be very good.
There’s nine creatures with the mana cost of G in the current standard. Some of them are just too slow ([scryfall]Renonwed Weaver[/scryfall] or awkward [scryfall]Kin-Tree Warden[/scryfall] or are closely linked to other color ([scryfall]Warden of the First Tree[/scryfall], [scryfall]Sunblade Elf[/scryfall]), which leaves us with just five:
[scryfall]Elvish Mystic[/scryfall] is in, no question. I didn’t like it when I was playing a similar deck last year, but now I feel I need them to be fast enough. Second turn [scryfall]Boon Satyr[/scryfall] or [scryfall]Deathmist Raptor[/scryfall] is very good.
The utility of [scryfall]Hero of Leina Tower[/scryfall] is largely dependent on how many tricks we play. We do have the four [scryfall]Aspect of Hydra[/scryfall]s, but are we playing [scryfall]Gather Gourage[/scryfall]? [scryfall]Epic Confrontation[/scryfall]? [scryfall]Titanic Growth[/scryfall]? Maybe even [scryfall]Ranger’s Guile[/scryfall] and [scryfall]Hunt the Hunter[/care] after sideboarding? I’d say we put her in. At least at this point.
[scryfall]Charging Badger[/scryfall] does have the nice benefit of having tremple and it might come in handy.
[scryfall]Servant of the Scale[/scryfall] helps with [scryfall]Avatar of the Resolute[/scryfall] and also leaves a nice bonus behind when it dies. Actually, I don’t see you being able to use the bonus very often, but you never know.
[scryfall]Sedge Scorpion[/scryfall] feels like a bit too defensive. If we were able to somehow give it trample, it would be nice, but I don’t see that happening.
There’s 27 of these, so I’m not going to go through them card by card, only the more interesting ones:
Avatar is in. More power then casting cost and two pips of devotion, plus trample. Yes, that is in.
[scryfall]Den Protector[/scryfall] is also a nice card. The pseudo evasion can be really good at times, because you can grow her with Aspect.
[scryfall]Heir of the Wilds[/scryfall] is a bit problematic. If we have enough power 4, it will work out nicely, but that would require testing.
[scryfall]Scaleguard Sentinels[/scryfall] is probably not stong enough. We won’t have any dragons in the deck, so he will never get the bonus, so he’s out.
[scryfall]Swordwise Centaur[/scryfall] is strictly worse than the Avatar, but might still make the cut, because of its two pips and three power.
[scryfall]Temur Charger[/scryfall]… hard to say. It would be good at times, but how often? Its easy enough to turn face up, at least and the ability is definitely strong.
There’s 29, but only four relevant ones.
This is a difficult one. I sort of like them all.
The flash on [scryfall]Boon Satyr[/scryfall] is extremely good. I’ve won so many games with it.
[scryfall]Deathmist Raptor[/scryfall] gives us a chance to go long. Also, if we play [scryfall]Den Protector[/scryfall] there’s a good chance we can return it to the table.
[scryfall]Reverent Hunter[/scryfall] gives us another way to benefit from the devotion we should have plenty of. It can be very big, but might sometimes strike out.
[scryfall]Yasova Dragonclaw[/scryfall] has trample and does trigger ferocious.
IF we go this high, I know exactly what we want:
So, with all that in mind, this might be a good starting point:
4 Elvish Mystic
4 Hero of Leina Tower
2 Servant of the Scale
4 Avatar of the Resolute
4 Den Protector
2 Swordwise Centaur
4 Deathmist Raptor
4 Boon Satyr
2 Reverent Hunter
2 Surrak, the Hunt Caller
4 Aspect of Hydra
3 Gather Courage
Note: There are other tricks you might consider. [scryfall]Life’s Legacy[/scryfall] might be very good. You can pump your creature with [scryfall]Boon Satyr[/scryfall] or [scryfall]Aspect of Hydra[/scryfall] and then cash him in after combat with this and draw a bunch of cards. There must be other good deck out there, but this is something you might want to try. Sadly, it doesn’t target (which would be nice with [scryfall]Hero of Leina Tower[/scryfall]).