Cards that don't need explanation - Mana dorks. Run all the available 1-drop ramp sources, as you want to hard mull for hands that play Freyalise by T3. Yes, that includes Boreal Druid (even though it makes colorless) and Birds of Paradise (even though it lacks elf synergy, it creates colored mana and chump blocks flyers in a pinch).
Avenger of Zendikar - The least mana-efficient/productive token generator in the initial stages of the combo turn, but the most mana-efficient/productive one mid-late combo turn. Usually want to drop after making most of your land drops.
Azusa, Lost but Seeking - Very powerful ramp piece that both lets you leverage all the lands in your hand as well as generate additional land drops mid-combo for Cradle/Nykthos, and even gas via Eye. Good with Lotus Cobra and/or Ramunap Excavator, and is 2 of the 4 extra land drops that this deck can generate. Can be found with most creature tutors.
Beast Whisperer - I've never been a big fan of Glimpse of Nature in this deck. While it's obviously a powerful card, it suffers from the fact that we need to dump a lot of our creatures to get to the T3 Freyalise, and mana tends to be tight enough that it's hard to "add in" a 1-mana instant in our early turns. Beast Whisperer solves a lot of these issues by virtue of being a creature. This means if you have no creature, its "worst-case" is a 4-mana 2/3 to block Freyalise and count for Cradle/draw effects. It also is extremely powerful if you ever untap with it, and provides a creature-based source of draw that isn't Regal Force.
Craterhoof Behemoth - Backdoor wincon in a pinch (potentially via Natural Order), but also generates lots of mana via Devoted Druid or lots of cards via Greater Good. Haste also lets you pick off a player if Concordant Crossroads is dealt with (though generally not necessary); best for enabling Devoted Druid, Greater Good, or being a third-string wincon.
Deep Forest Hermit - A new card from MH, Deep Forest Hermit is basically a strictly better Deranged Hermit for this deck, which was always one of the best token producers.
Deranged Hermit - The most mana-efficient/productive token generator going into/in the early stages of the combo turn. Common GSZ/Chord target, as 5 bodies for 5 mana is premium rate and a sweet spot.
Devoted Druid - Single-handedly ramps into Freyalise on turn 3 (by making 2 mana). On combo turn, can easily make a lot of mana via Craterhoof Behemoth, either by having controlled her since the beginning of your turn or in conjunction with Concordant Crossroads or Earthcraft.
Dosan the Falling Leaf - A tutorable City of Solitude. Better than City due to the overwhelming amount of creature tutors in the deck. Generally your go-to tutor target in the late stages of the combo, when you're relatively certain you have the resources to spare or when opponents obviously have kept up interaction.
Elvish Archdruid - A slightly more expensive Priest of Titania. The pump on your Elves can be relevant with Greater Good if you have a lot of lands on hand (draw 2 discard 3 can be reasonable), but also has unfortunate negative synergy with Skullclamp. Can help ramp out Freyalise on T3 when played T2.
Elvish Spirit Guide - While I will stick with the fact that Freyalise doesn't really benefit from the "usual" fast mana that costs CA like Lotus Petal, Chrome Mox, and Mox Diamond, Elvish Spirit Guide benefits from one simple fact that isn't true of Petal and the Moxen: It's a creature. While in most decks casting your spirit guides is a sign of desperation, in Freyalise it's a very viable option that she's happy to have access to. While the primary function is obviously to pitch for mana, the "2/2 for 3 option" provides a viable option for when you're mana-heavy to develop a blocker/creature-counter for Freyalise. It's also an elf for the elf synergies, and can turn your Summoner's Pact into a Lotus Petal if you're short on green mana on your combo turn. It can also come as a surprise if someone tries to Spell Pierce your general, or something similar. It's a very versatile card, and the fact that it doesn't "need" to be a Lotus Petal provides a large degree of flexibility.
Eternal Witness - A tutorable Regrowth. Better than Regrowth due to the overwhelming amount of creature tutors in the deck. Forms an interesting infinite with Survival of the Fittest and Crop Rotation (explained later). Also tutorable with Woodland Bellower, and one of his primary tutor targets.
Fierce Empath - Run primarily for tutor conversion - converts Green Sun's Zenith and Chord of Calling into Ulamog/Kozilek triggers, and Woodland Bellower triggers into gas when flooding out. Elf for elf synergies, can be Skullclamped. Can also tutor for nonlegendary creatures that cost 3 or less in turn via Woodland Bellower.
Hornet Queen - On the upper end of tokens/mana, is also the best general-purpose NO target when under 6 lands. The tokens she generates are valuable for holding off pressure on Freyalise, especially from flyers that the deck otherwise has trouble with.
Joraga Treespeaker - Worse than Sol Ring, but better than Worn Powerstone. When played on turn 1, guarantees a T3 Freyalise while also being mana-neutral on turn 2. Full leveling is rare but worth keeping in mind for corner cases.
Kozilek, Butcher of Truth - Primarily run for his GY shuffle clause to set up several interesting infinites with Earthcraft and/or Greater Good as discard outlets. In a pinch is a 10-mana draw 4 (which is surprisingly relevant - draws additional 12 and shuffles GY with Greater Good), as well as turning land tutors into 15-mana draw 4 via Eye of Ugin. Finally, way of cycling through deck in combination with Temur Sabertooth and infinite mana.
Lotus Cobra - Ramp dork than can be played on T2 to ramp out Freyalise T3, also does it by himself in conjunction w/fetchland. Goes crazy with extra land drops and/or small Genesis Waves.
Manglehorn - Powerful artifact destroyer and "backup" Reclamation Sage (though more powerful in particularly shutting down artifacts). Common tutor target with Woodland Bellower.
Marwyn, the Nurturer - While by far the "weakest" of the elf-matters mana generators (as Marwyn has to be on the battlefield before you play other elves), Marwyn still makes the cut in the end. She grows off Freyalise tokens, becomes a valuable blocker, and has very positive interactions with Craterhoof and Finale. She also is a "second source" of ramp with any 1-drop ramp to get to T3 Freyalise. All of these factors together means she makes the cut, though she is likely the weakest mana dork in the deck.
Oracle of Mul Daya - While more expensive for less extra land drops than Azusa, is an important second tutorable way of getting an extra land drop. When played early can be used for value in playing lands off the top of the deck, though this usage is incidental.
Priest of Titania - Powerful ramp source in conjunction with Freyalise's tokens. Arguably better than Elvish Archdruid in that she doesn't shut off Skullclamp.
Ramunap Excavator - Efficient way of recurring Cradle/Nykthos with extra land drops/by Strip Mining/Crop Rotationing them (yes, this does come up fairly frequently). Less powerful than Eternal Witness in general, but is better in certain niches (ability also doesn't use stack when put into play off tutor). Part of Woodland Bellower toolbox.
Realm Seekers - Powerful land tutor/Greater Good Enabler. As a land tutor, seems expensive (9! mana), but is the only reliable way of turning creature tutors into land tutors. Most of the powerful lands in the deck (Gaea's Cradle, Nykthos) are mana-positive even then, especially since he fetches Deserted Temple once you have an additional land drop. Also tutors for Eye of Ugin -> Kozilek/Ulamog if you flood out. For more detailed information, see Sylvan Scrying.
Reclamation Sage - Very powerful tutorable artifact/enchantment hate and part of primary Woodland Bellower toolbox.
Regal Force - Primary tutorable draw engine, and most consistent secondary draw effect either after Freyalise's ult or primary in lieu of Freyalise's ult. First tutor target once you have sizable board, either during combo turn or prior to combo turn as insurance against Wrath effects.
Temur Sabertooth - Core tutorable combo piece of deck in conjunction with Earthcraft + Utopia Sprawl/Wild Growth (infinite mana and tokens via Deranged Hermit) or Concordant Crossroads with a mana dork that taps for at least 5 mana (Elvish Archdruid, Voyaging Satyr, Priest of Titania). Can create infinite mana via Craterhoof+Devoted Druid if you control a total of at least 11 creatures. Being tutorable, is part of some compact combos with Survival of the Fittest (explained later). Can be value engine with a token producer or Regal Force if you're not at critical mass.
Ulamog, the Ceaseless Hunger - Functions as both an infinite mana end-line in combination with Temur Sabertooth to "kill" table without having to worry about combat, and as a tutorable uncounterable way of dealing with various hate pieces. When flooding out, can be fetched with land tutor for 15 mana via Eye of Ugin (in general Kozilek is preferred if you have enough mana to continue going off, but Ulamog can more consistently impact the board if you foresee yourself having to pass the turn). Attack trigger can shut down opposing combo decks after one swing.
Voyaging Satyr - The only of the land-untapping dorks to cost less than 3 mana. Argothian Elder is simply too expensive at 4 mana (never can be played T2 to help power out an early Freyalise), and even the 3-drop ones are slightly too expensive if overall more feasible. The ability to untap lands is powerful, and those can range from Nykthos or Gaea's Cradle during combo to make lots of mana, Ancient Tomb before combo to make lots of mana, or even just Pendelhaven/Maze of Ith/Eye of Ugin for "value," when necessary. When all else fails, a 2-mana mana dork.
Wall of Roots - Costs 1 mana every turn but the first, and is thus close enough to a 1-drop dork. Also filters back the green mana it consumes, which is nice (mana multiple times/turn cycle can also be relevant with limited suite of instants and Top).
Wood Elves - Primarily a way of ramping that doesn't expose yourself to wrath effects, but also can be a "token generator" by being 2 bodies for 3 mana via Dryad Arbor. Can be tutored for by Woodland Bellower for 3 bodies for 6 mana - a rate comparable to Hornet Queen.
Woodland Bellower - Most of the relevant tutor targets have been discussed in their relevant sections, but nonetheless is a very powerful tutor that also develops a body to the board. The body can also be a free body if you were TNNing for a 3- drop, and the body is valuable with Greater Good as well.