Hey, nice upgrade of the precon.

Lathril + Immaculate Magistrate + Copperhorn Scout combo scales to make Lathril bigger each turn you attack which can create more Elves each time and it lets you use Lathril's tap ability with all the Elves she just created after combat. Timberwatch Elf can replace Magi, but the pump goes away at end of turn. Marwyn, the Nurturer can make a lot of green mana with Magi/Timberwatch + Scout to use with a mana sink such as Ezuri. Scout's ability to untap all other creatures you control whether they attacked or not is powerful with big mana producers and a mana sink. Magi + Joraga Warcaller is another good interaction to make all Elves huge.

Birchlore Rangers has impressed me because of his interaction with Elf tokens. Able to tap pairs of them to make mana the turn they're created which is nice to cast instant speed spells or pay activations such as Ezuri's regenerate and Miara's draw when you're tapped out. It's also helpful that Elves can make green or black mana. Nullmage Shepherd has also impressed for some of the same reasons. These tapping effects along with other Elves who tap such as Lathril and Archdruid, etc. become even better with a repeatable way to untap all Elves on each opponent's turn such as Seedborn Muse and Quest for Renewal .

Instant creature tutors are helpful especially Chord of Calling with Elf tokens, but also Shared Summons which can put two Elves into your hand. Elves of Deep Shadow is in my opinion the best one drop mana Elf with Lathril because he's reliable ramp to cast her without needing a black source from a land.