Shiko and Narset, Unified, as well as Aligned Heart seem like the best cards among the new offerings, but any spellslinger strategy has tons of new tools to choose from in this deck.
This includes cards like Jokulhaups destroying your lands, Winter Orb and Stasis preventing your lands from untapping, Grand Arbiter Augustin IV making your spells cost more, or Blood Moon ruining your colors
Tribute to the World Tree Consistently drawing cards is one of greens weaker areas in Magic
Enough effects that do a damage to everyone or every opponent, like End the Festivities and Creeping Bloodsucker, and your 1-drop 1/1s enter as 4/4s
Open your boosters and find out Each booster pack contains one of 121 possible card lists so there are over 14 000 possible 40-card decks
And if you have Spell Mastery (not too difficult to pull off), you get to dome them for the creatures power too