Beacons of Remnant (RWBY Set Idea)

{Spoiler}{Current season based classification-Spoilers} -Perhaps use normal MtG types for classes of entities as a baseline? It's not directly applicable, so some creative license needs to be used. My impression is Remnant's Gods may be the only entities that seem to 'planeswalk' but as to their actual effect in the story line they are pretty typical 'gods', having aura like effects like Scarab God, but otherwise not doing anything super special. On the other hand, Ozpin is not typical of a creature in any way, and while a standard creature version of him might have some sort of recursion or regeneration, his effect on the battlefield seems more like a Planeswalker to me: one who does not directly attack or block under normal conditions, but instead has an general beneficial effect on your board state. This would also describe Salem. I'd put the 4 seasonal themed 'Maidens' as Enchantment Creatures at Legendary.

{Spoiler}{Notes on cards}
Nukalavee: Not sure if it throws balance off, but it was a pretty powerful creature requiring teamwork, so maybe add 'must be blocked by 2 or more creatures'? Fear seems like it would fit, however the actual mechanic does not, especially if the set theme is 'Hunters VS Grimm', where none of the hunters could block a Grimm attack (defeating the purpose). 
As to the argument about 'new creature type due to flavor' it seems that there would be a better argument if there's a mechanic that triggers off of the type, such as a 'Badlands' land that generates Grimm and only Grimm when there is conflict? such as 'whenever Human attackers are declared, you may search your library for a Grimm creature with power/toughness 2/2 or less and place it on the battlefield under your control' or 'whenever Human attackers are declared, place a 1/1 black Grimm creature token on the battlefield under your control', but this is still a weak argument for a new creature type. (I'm trying to use Rats/Swarmyard type mechanics to justify it, since I like it, but it's hard to make it a strong argument). 

Ruby Rose: I mentioned perhaps have 2 variants of this card, student and graduate, and I mentioned Haste, but First strike may be better. Someone who's better at gauging MtG flavor would be more knowledgeable than I what 'speed attack' would be represented best by: First Strike, Haste, Flash, Double Strike ..? Her semblance implies traveling fast at short distances, striking quickly multiple times, and limited flight, but these don't translate well.  I think the 'Heroic' mechanic works well here as she does seem to draw the best out of others, but I'm not thinking that it should be a major theme (or else every main character ends up with it or some version of it)  She is a soldier, and soldier themes work well with her.
Critique: I know she wears red and 'Ruby Rose' screams red, but in MtG, red is more about wild passion and emotion, where as Ruby seems more attuned to 'what's right' which is a White trait.  It's going to look wierd, but she's more of a White Soldier than a Red Goblin .  Yang, on the other hand, is hot-headed and reactive, making her red or green (probably green, due to growth, but family is important to her, which is red)

Beacon Academy: Slight flavor changes- the title implies it's the only school that trains hunters (which, sure, in the first few volumes of the series we don't know much about the other 3 academies) Also, I'm not sure what flight has to do with beacon, it seems arbitrary.  Depending on how deep you are going with the set, might I suggest something along the lines of 'T, tap a fall maiden: search your library for a Relic Artifact and (Relics not defined yet).  Keep in mind that there are 2 cycles of 5 3 color land combos, 4 academies, some other schools mentioned (Signal), and that it seems that the Relics (and associated schools) have specific themes such as Knowledge, Creation, etc, which there are defined MtG themes in colors already established.  Might look at what guilds are closest to which schools? (removed notes due to length)

Dust: seems more like this might work like Clues or Treasure: "Sacrifice this artifact to add **(energy tokens)".  This makes it more of a 'power artifacts and enchantments and creatures' than 'bring stuff into play' artifact.  It loses some of the fun of color (specific dust enhancing specific effects) but that would be too high of a level of complexity, perhaps.

Schnee dust mines:  If the change to Dust is considered, then Dust Mines of any kind would produce Energy, not Mana. Within a draft environment, this might not be too much of a drag on gameplay (loss of mana-producing lands in the set). If considering Commander/Brawl or otherwise mixing with other planes, perhaps make 'normal' lands or artifact lands (even add colored mana) with the additional 'T: create an artifact token with 'Sacrifice this artifact: add **(Energy Counters)'

Other academies:
Shade has good theme/flavor with deathtouch, though again I'd suggest a reference to the relic or it's theme. 
Atlas would be better to have Flying, as they are always depicted with a flying military, but again, I'd go with Relic themes for the schools, or look at Tolarian Acadamy as a template with mana production based on relic theme, then add mana producing lands based on city or country basis.
To a degree, then you could have each school add mana based on some aspect, and make Salem's land produce Black (for each Grimm you control?)
I'll agree that tri-lands are better than taplands, but some areas are hard to attribute more than one or two MtG themes to (such as Salem's tower is probably strictly Black).  I wonder if it would be better to craft the base focuses and templates for the set, craft the world in cards, THEN fit powering the world in basic/dual/tri/utility lands.  Might also considering culling some things that end up with too much of one thing and pushing these into a second set (though that's a LOT more work).

In this way, even though the White Fang are considered 'bad guys', they are a passionate, destructive force driven by justice, making them Boros (Red/White).  They would have started out as R/W verging to R/G, but are now R/W verging on R/B

Blake: (R/W) The same can be said for Blake, who's father is Lion like (white) and mother could be said to be family oriented (red).  Adam is also driven by justice and passion, but is also self-centered and corrupt, adding black. (I don't see Blake as having anything to do with Black, other than she wears black.)  To a degree, I don't see Blake as having duality of character. She's concerned about the things she was involved with, but she, herself, is pretty straight forward, wanting to do what is right almost more passionately than anyone else. She despises the wrong, and in this way she does not have any Black to her. (that was adapted from something else I was writing) 
Blake Belladonna, in my opinion, should be Red/White (nWR), may have vigilance, but also should have evasion, referencing her Semblance, perhaps Shadow or Ninjitsu?  Hmm.. it would take some work, but it would be interesting to be like "T: place a 0/1 Illusion Artifact Token on the battlefield blocking target attacker. with "sacrifice this artifact at the beginning of the next end step".  Activation cost could also be Energy based, so it can be recurred in one event if this isn't too OP.

Weiss Schnee: (U or U/B or W/U) This seems less epic than your Yang or Ruby (though she does seem like a supporting character). It's hard to get swordplay and adept spell control into a creature without complexity or OP, unless you put something in like Bushito?  If she does fit a slot in your set for Dust production, though, I'd suggest "During your upkeep, add a Dust artifact token with 'sacrifice...etc'", since it seems like wherever she is there's never a shortage of Dust (instead of a one-off ETB), unless this makes it OP. Color: Weiss is mostly about precision, studying, and that having enough knowledge about tactics and whatnot is most important. She does want to do what is right, but is extremely self centered.  Her importance on knowledge and training is more what her sister and homeland has drilled into her, giving her a fickleness that's sorta black (it's too hard!) sorta white (military precision and doing what's right at all costs), sorta blue (knowledge is power)  In reality she's so bland of a character it's really hard to put any real flavor into her.

Yang Xiao Long: (G, or R/G) (I need to study Heroic mechanic more, looks like it's flexible enough to work on specific... ignore above?) Yang's pumping is temporary and has limits. I'm not good at balance and technical MtG verbage, but to be more on-flavor how about something like: "Trample. If ~ would be dealt damage, ~ is +1/+0 until end of turn for each point of damage she would be dealt." and perhaps make her a 1/3 or 2/3 to start with? In this way, she doesn't get super OP in long games, but you could use other sources to hit her hard, regenerate her, then smash face. (depends if you envision a game as a single battle or a war... in a war she'd boost many times, in a battle she'd be continuously building) Color: she's green as she's kind of the Mindless Brute that Grows, but she's also quick to react to destruction, making her slightly Red.