DedWards

Big wheel effects like Wheel of Fortune, Wheel of Fate, and Collective Defiance plus discard punishment effects like Megrim, Liliana's Caress, and Waste Not can help you win faster. Use Howling Mine and the like to keep the opponent's hand full. Sweepers like Anger of the Gods and Damnation alongside spot removal like Fatal Push and Lightning Bolt help keep the board clear.

I think there's a Chandra with a Wheel effect.

Blossoming Defense is your friend. While Supernatural Stamina will get you another explore trigger, you will lose any +1/+1 counters the creature had. Blossoming Defense doesn't get you another explore trigger, but saves the +1/+1 counters already there. This is good for Wildgrowth Walker and an animated Shadowed Caravel.

I know you're on a budget, but I strongly suggest getting Fatal Push asap. You could probably use Walk the Plank in the meantime, but you definitely need removal.

Memnite might be better than Ornithopter.
Suspend Worldfire, cast Memnite, Delay your own Memnite. Manipulate time counters to get them in at the same time, let Worldfire resolve first, the attack with the hasting 1/1 for the win (creatures coming off suspend gain haste).

There's a card that works similar to Fatal Push that most people tend to forget about: Tragic Slip. Same cost, similar trigger for awesome.

If you're looking for another 1 drop creature, Monastery Swiftspear or its Weird "brother" Blistercoil Weird comes to mind.

Also, with such a low curve, you could drop to 17-18 lands, maybe lower.

You may need more card draw (Serum Visions, Sleight of Hand, Ancestral Vision, etc) and more ways to manipulate your suspended cards (Clockspinning, Fury Charm, Jhoira's Timebug, etc.)

I've tried Aeon Chronicler myself, and I've found it requires more mana than it's worth

I've yet to try it myself, but Deep-Sea Kraken could be a decent alternative win condition.

I agree on Sphere of Safety. Ghostly Prison does a decent job too.

Replenish is not Modern legal.

Stuffy Doll shenanigans are counterproductive to Sphere of Safety / Ghostly Prison.

The only Extort card worth playing is Blind Obedience as it fits the rest of the deck pretty well.

Win conditions I think would be good is Luminarch Ascension, which spews out 4/4 flying angel tokens, or Starfield of Nyx, which animates and reanimates your enchantments.

Decks like this is why I've started including mass enchantment hate alongside my mass artifact hate in my sideboards. Good job at being more annoying than a turn 2 Blood Moon :P (I run Ponza)

The randomness and extra mana reliability is the main problem. Cards with similar effects, while costing more initially, mitigate the mana liability by giving other bonuses and / or delay the exile effect. Like Chandra, Torch of Defiance which gives you other options the turn she hits play and Shocks the opponent if the card isn't played. Or Outpost Siege (calling Khan) delays the exile to the next turn, allowing you to use the mana used to play the card giving the effect on the new "extra" card.

Abbot isn't bad, it just has too many cons for it to be viable in the fast pased meta of modern.

I'm taking a break from Ponza. We're trying to grow our club and I don't want to scare away new players.

Interesting build. I really like how Dromoka's Command and Dawn Charm can be mainboard options to counter burn spells.

I personally prefer Ethereal Haze over Holy Day. It fills the exact same role, but with a minor up side of preventing damage from things like Vexing Devil's ETB 4 damage from sacrificing or Grim Lavamancer's tap ability.

I'm not a fan of Rites of Flourishing. The draw part I don't mind too much, but giving the opponent extra land drops is VERY bad. Temple Bell might be a better replacement at the same cost, just colourless, and you get to control when the draws happen.

Bramblecrush seems like an odd sideboard choice. What are you planning to bring it in for?

Currently, it's "banned" in Standard because the Battle for Zendikar block is no longer part of Standard. It is legal in all other formats, to my knowledge.

As for why it got banned while BFZ was in Standard, Collected Company was largely to blame. To quote Wizards:
Reflector Mage—Our data showed the White-Blue Flash deck was too powerful against the field, and Reflector Mage has been on players' lists of most-disliked cards since the days of Collected Company. Other cards were discussed to check White-Blue Flash, but Reflector Mage came up time and time again as both frustrating and a targeted way to diminish the White-Blue Flash deck.

Worth testing, no?

Ral Zarek would be an interesting inclusion. His [+1] can tap down a creature for Swiftspear to get through, or tap a land to prevent counter / kill spells for what you're about to play, all while untapping one of your lands, pseudo ramping you. His [-2] pings off creatures, or brings the opponent's life down into a killable range. Then, of course, there's his [-7] that works with Krark's Thumb to buy you up to 5 extra turns.

I tried Hunted Horror in earlier builds. Due to the lack of removal, giving the opponent anything bigger than a 1/1 is actually bad. Additionally, the creatures the Horror gives have Protection from Black. The deck also gives a ton of creatures, so despite the horror's impressive 7/7 body and trample, which can't block the 3/3 centaurs it gives, you can't really attack without it dying.

I even had Sleeper Agent in earlier builds. Giving anything bigger then 1 power tends to bite back too hard for this deck to handle.

Hissing Miasma is an all star in this deck, especially when you can fog. Which is what makes Batwing Brume so awesome, it fogs and drains.

Because Stronghold Discipline requires creatures in play, mass kill is counterproductive. Killing Wave isn't a bad card, but it'd be contending with Stronghold Discipline for a slot.

Those really depend on how readily their nontoken sides will die.

I have a Modern / Pauper token deck that may interest you. While it contains the Presence of Gond + Midnight Guard infinite combo, it's actually greared towards casting Sprout Swarm multiple times.

Probably because Green and White are most pro creature token. A quick Gatherer search will show you that G+W has a ton of cards that make multiple tokens for relatively cheap mana cost and / or ways to boost tokens you're making.

Intangible Virtue makes any token deck a lot better.
They both have 4 mana token doubling enchantments: Anointed Procession and Parallel Lives.
There's a two card infinite token combo: Presence of Gond + Midnight Guard (no haste, but that's not a GW thing anyway).
Anyone that's played with or against Sprout Swarm knows how quickly it can swarm (even if not infinite).
There's a reason Selesnya from original Ravnica was heavily token based.

Shall I go on?

Belligerent Brontodon is another one sided deal damage equal to toughness card.
Verdant Sun's Avatar gains you life equal to its toughness and the toughness of each of your creatures entering after it.

Pia's Revolution for all that artifact sacrificing going on? Not sure how well it'd work with Slag Fiend though.