First- let's examine the role of 4-drop green creatures in the cube.
Green's primary strengths are the abilities to accelerate mana quicker and play higher quality creatures than any other color until the late game. A green deck, as such, is either trying to ramp or use big green guys to top a mana curve. Some green decks only use green utility creatures such as
Fauna Shaman and
Ramunap Excavator, but these guys have little to do with the 4-mana slot.
Green 4's are usually going to be the first true "fatties" played during the game. As such, they should generally be on rate or bigger than the other 4-mana creatures in the cube with little exception. This way, you can allow for ramp decks that are only trying to accelerate early instead of all throughout the game. Being able to go 4-drop 5-drop 6-drop a turn earlier than the opponent can often be just as good as 5-drop 6-drop 7-drop if the 4 drop is good enough.
Let's examine each of the 4-drops you placed in front of us and discuss a couple others you missed.
Beast Whisperer- Only some decks want this. The "Elf Ball" decks in which something like this would truly shine take up a lot of space in the cube and usually aren't worth supporting. Although this can be used in the mid game of some ramp decks to turn mana dorks into cantrips, it's usually just better to run a beefy creature in this slot.
Bramble Sovereign- Cultic Cube did a great video about this card. It's a good option for ramp decks, but also any green deck trying to go wide, such as G/W Hatebears.
Centaur Vinecrasher- You need a lot of support for the "lands" archetype for this guy to truly shine, but I can see him being good in some decks. This card is fairly narrow in a fetchland-free environment, but is barely playable otherwise. It's very bad without support.
Vengevine- The calculus on this card is simple. If your cube has decks which will be casting 2 or more creature spells per turn, play it, otherwise, don't.
Vengevine is only explosively good in modern because of the plethora of 1 and 2 cost creatures which can both be used to get Vengvines in the yard and get it back into play.
Master of the Wild Hunt-This card was a cube staple when it was first printed, but now adays I feel like it's just a slower
Polukranos, World Eater. Sure, you can theoretically re-use if it doesn't die to removal, but ultimately I don't think it's fast enough to justify inclusion in most modern cubes. Green 4s have evolved past it I would say.
Oracle of Mul Daya-unless your green decks are trying to hardcast 15 mana eldrazi like
Emrakul, the Aeons torn, there is no point in running the oracle. This card's place on the mana curve means that it can't be slotted into decks that aren't dedicated to ramping, but it doesn't come down until turn 4 without other support. Being able to play an extra land every turn is nice, but most decks can't use this ability to it's fullest extent. It has fun applications with
Experimental Frenzy, but that's the only place this belongs other than eldrazi ramp.
Oracle of Mul Daya doesn't bring anything to the table that traditional creature and enchantment-based ramp can't handle. If you're not trying to ramp above 8 mana, don't run this card.
Polukranos, World Eater- This is my favorite green 4-drop. It can come down early in any deck running a 1 or 2 mana mana dork, it has an above-curve body, and it can act as a pseudo-board wipe in the late game. Although Polukranos gets worse in extremely high powered environments, he's still a reasonable pick even in Vintage cubes. Love your Polukranos and never let it go.
Thrun, the Last Troll- This card is un-interactive and just generally un-fun to play against. The only way to beat this card seems to be a
Wrath of God effect. Although Thrun acts as a counter to control decks, "needing" to include this card is less of a sign that green needs a buff and more of a sign that control needs a nerf.
Here are some good cards you missed:
Chameleon Colossus- The classic green 4-drop and the God Father to all modern green 4s. I like this card for it's protection from
Terror and other black-based removal.
Ripjaw Raptor-This card is so underrated it's not even funny. It's a card that aggressive decks can make use of due to it's stats and built-in card advantage, and something ramp decks are ok with lying down as a stonewall to aggro. Most red aggro decks can't beat this without dealing damage to it at least twice, meaning you get to draw two cards.
Voracious Hydra- I'm counting this as a 4-drop because that's the place it will be most likely played in the absence of it's fight effect being used. It plays somewhat similarly to the
Territorial Allosaurus except you trade a little size for flexibility. At 4 mana, this is either a 4/5 or a 2/3 that kills their
Dark Confidant when you play it. However, it comes with the ability to be scaled. For 7 mana, you get a 5/6 with a fight effect, which is very good.
Nightpack Ambusher- The sole reason Wolf Tribal has existed as a viable standard deck in the last 5 years. You can play this card on your opponents turn, and then just make free wolves whenever you don't cast a spell in a turn. This card's only downside is that it is only exceptional in U/G flash strategies, but that's not a bad thing at all- it signals an archetype without actually needing to be played in that deck.
Green 4s are probably my favorite section in the cube to build with and talk about. There are so many fun options- but some are better than others. There are a ton of great cards that I didn't even mention today-
Shifting Ceratops,
Territorial Allosaurus,
Nylea, God of the Hunt,
Questing Beast,
Elvish Piper... the list goes on and on. Ultimately, just pick the cards that you think are the most fun to play, with the understanding that there are always 20 other equally viable options waiting in the wings if something doesn't work out.
