This is the "vanilla" decklist: Rebuilding the deck is basically the usual process - remove ETB tapped lands, substitute in "better" aka typed duals, more basics (yes more, most precons have unnecessary non-basic duals, and then run cards like Kodama's Reach and Fertilid, such that they can quite easily run out of basics to search for.) Focus on the core aspects or the deck - getting +1/+1 counters out on small creatures and spreading them around, then leveraging the growth in +1/+1 counters via varied abilities to turn small creatures into big fatties
Weve seen this idea before, with Hidetsugu, Devouring Chaos in Kamigawa: Neon Dynasty and Cavern of Souls in The Lost Caverns of Ixalan
In other words, that's four mana of value you can gain the same turn she enters the battlefield
Since they were on the play, they are ahead in the race by nature
Weve assembled an Rogues Assassins Gallery for you to meet
Failing any of that, it was all modular, so anything he couldn't finish was easy to pull out, and everything had simpler alternatives