Card Choices

Hallar, the Firefletcher functions almost like a Walking Ballista in this deck with the kicker cards. Trample is also nice you can just throw Blackblade on him and swing in for 20/20 trample lategame.

Marwyn, the Nurturer can get out of control with multiple Constrictors on the board since all your other creatures are elves. Her tap ability is also useful paying for kicker costs and casting Menagerie.

Rishkar, Peema Renegade just an overall great card in this deck. Is a legendary for Mox/Blackblade, is an Elf for Marwyn, is a 3 cost creature to fetch from Menagerie, and gives free counters on top of all that. Also turns your creatures into Llanowar Elves.

Rashmi, Eternities Crafter another great legend elf. Initially I hadn't put this in but the deck struggled in card advantage and this was a great pickup. Even if you don't hit a playable card you still get the draws and it even works when you play instants on the opponents turn.

Winding Constrictor counters.

Wild Onslaught more counters.

Song of Freyalise more counters. And some mana fixing if you need it.

Uncage the Menagerie the heart of the deck. Play this for X=3 and you can fetch your 3 main elves Hallar, Marwyn, and Rishkar. If you have Rhonas sided in you can fetch that as well. Otherwise you can play for 2 to fetch a Constrictor or 4 to fetch Rashmi.

Blackblade Reforged equips on almost all our creatures and has extra synergy with Marwyn giving you all the green mana you would ever need. Also serves as sac fodder for Goblin Barrage.

Mox Amber like Blackblade functions with almost all our creatures and again serves as sac fodder for Goblin Barrage.

Goblin Barrage I originally went with Shivan Fire here but this just seems strictly better. If you have an extra Blackblade or Mox in hand you can sac the one you have on the board to get in some extra player damage and it's still cheaper than a kicked Shivan Fire.

Aether Hub solid for fixing mana early. Can even get extra energy if you already have constrictors out.

Unclaimed Territory since the deck is basically Elf tribal you can use this to pay for your Blue or Red symbols. (This is the only way in the deck to pay for Rashmi). Naming Snake can also be helpful if you need Black mana for Constrictors.

Wincon

The main wincon's are pumping Hallar with counters and then using your cheap kickers to trigger his ability and ping them to death à la Walking Ballista. Alternatively just Blackblade on a creature (preferably Hallar for the trample) and swinging in for a million damage.

Sideboard

Fairly standard sideboard against current meta decks.

-Side in Abrade against aggro or artifact heavy decks. Side in Fatal Push and Harvesters against aggro. Blackblade is weak against aggro since you just get chump blocked trying to swing in so you can side that out and maybe like Goblin Barrage and Wild Onslaught since those are slower.

-Duress and Spyglass against control/combo. Shuts down Teferi and all the annoying counterspells. Against combo you can remove their vital combo pieces or turn off their stuff like Aetherflux Reservoir.