Apparently this sort of deck is getting a lot of traction in modern at the moment which I find quite interesting as it has been an increasingly popular direction to go in cube. I added enchantment ramp to the cube a while back and it has helped maintain a bursty ramp style of deck in green that isn't vulnerable to burn and mass removal in the same way as those leaning on Gaea's Cradle and creature ramp. It has also greatly increased the power of Arbor Elf and Garruk Wildspeaker! There are a lot more advantages to using enchantment ramp beyond safety and abuse with untap effects. Those are the main two certainly but you can make use of nice synergies such as Enchantress effects or delirium more easily with so many extra enchantments in your list. That is basically the premise of the deck, enchantment ramp as the core combining with Nykthos to empower delirium and with untap effects to double up on ramp earlier in the game.
The modern shell of this deck is very similar to most incarnations of green ramp decks in the cube. The modern build has a bit more reliance on tutors and a few less old broken cards it can use. The main difference is that I am not running Burning Tree Emissary in this list, you don't have the consistency in cube to merit wasting a card on a 2/2. The extra burst it provides does not offset the power per card cost in cube.
It is not all upside, by using the enchantment ramp over creatures you lose some consistency on your Overrun kills via Garruk and Craterhoof which are your main routes to victory. You also lose some general utility in protecting and threatening planeswalkers. The list I have given below is not super refined or tested, it is an example list showing the various cards and ratios you want to be looking at when doing this sort of thing in cube. It is threat light compared to my more classic versions of ramp green but this list makes up for that with more tutor, dig and recursion effects than I normally run. It can get away with less threats overall using only the premium ones it needs in combination with the dig and tutors. While it is space efficient it is a little rougher when you come up against lots of removal and mill effects.
Oath of Nissa
Magus of the Candelabra
Rofellos, Llanowar Emissary
Nissa, Voice of Zendikar
Growing Rites of Itlimoc
Courser of Kruphix
Eidolon of Blossoms
Nykthos, Shrine to Nyx
I didn't even bother running Cradle in this list. While it is great it comes with two vulnerabilities, doing nothing until you have dorks and doing nothing again when your dorks get killed. Low land hands with Cradle can often need throwing back where you could have kept if it were a forest. This deck doesn't need the Cradle as much as other ramp versions as it has more things that generate multiple mana and is more focused on safety and consistency.
I ran an Eidolon of Blossoms as a source of card advantage. It is basically a direct replacement for Oracle of Mul Daya that you can do in this build. I like most of the things about it but it does make me want Explore effects more. Getting a load of land clogging up your hand that you can't put to use is annoying and with a decent amount of draw and not all that much pulling lands out of the deck I can see that happening from time to time. Perhaps you can run both the 4 mana 2/2s!? If not I would at least like to find some room for Explore.
Another mini theme you can run that I did not in this list is a delirium one. Traverse the Ulvenwald is a lovely card in this list finding all the things you want it too once you have delrium. Ishkanah is immensely powerful even with no access to black mana and these kinds of deck have sufficient mana production to go all the way up to Emrakul, the Promised End. Having Ishkanah and Emrakul in your list, especially with a tutor for either, greatly reduces the pressure on your Craterhoof Behemoth as the win condition which in turn reduces the pressure on you to maintain a high creature count. As you can see, green ramp is an immensely deep and diverse deck in how you can build it in cube. Even the different directions you can take it have themselves multiple distinct things you can then do.
Walking Ballista feels a bit like a must in this non delirium version of the deck. My experience of using Nykthos is that it tends to be overkill mana. While it may not have the same burst potential as Cradle it does tend to produce rather more mana, both in one go and over the course of a game. As such you want a powerful mana sink and for that none come better than Ballista. With it being such a significant role filler in the deck I ensured all the tutors I played would be able to find it effectively which sadly does rule out a lot of the exotic stuff that is being abused in modern.
Earthcraft and Magus of the Candelabra are quite full on. Neither do huge amounts without a land that taps for multiple mana, specifically a basic one boosted that way for the former. These are probably things you can cut for more stand alone cards, likely alongside Growing Rites. I mostly wanted to showcase some exotic and unusual cards! I always like it when a deck lets a card shine in cube these cards have multiple things going on here that make them especially well suited to the list.
I didn't bother adding in too many utility dorks which I likely should have. Acidic Slime and Scavenging Ooze are the most appropriate and appear in most modern lists. The lower threat count and high tutor count makes such inclusions pretty sensible. Failing that a little more utility disruption might well be found in planeswalkers such as Freyalise, Karn and Ugin. Not to mention all the Golgari ones! If the exotic cards like Magus then I would be looking to replace them with some disruptive tutor targets or indeed more dig effects.
Below is a list of many more cards ranging from the exotic to the every day, from the limp to the powerful. The main, if not only thing, they have in common is that they are also suitable cards for this kind of deck. There is no huge logic to this list other than it being cards I considered while making the list which I felt either sad or bad about not having included!
Xenagos, God of Revels
Candelabra of Tawnos
Wall of Blossoms
Vessel of Nascency
Oracle of Mul Daya
Traverse the Ulvenwald
Chord of Calling