Some cards that attract my attention here for Modern:
Archon of Emeria - might be too slow at 3 cmc, although it could be more playable if you are on the play and/or using some kind of ramp, perhaps in a GW hatebears list.
Luminarch Aspirant - this also feels like it might end up doing nothing too easily, but it seems pretty cheap for the effect if a deck ever needs one counter on each of your turns.
Charix, the Raging Isle - feels like that 17 toughness might be useful for some kind of weird deck or combo some day, especially with how it increases the cost of removal against it.
Confounding Conundrum - ramp and/or fetch hate that comes down soon enough to matter and cantrips? Might actually see some play!
Maddening Cacophony - I could see this fitting into some mill decks
Ruin Crab - hedron crab 5-8 for mill, although not self-mill things like the original can, it does have an extra point of toughness
Sea Gate Stormcaller - It's no snapcaster mage, but it seems like it might do something worthwhile in it's non-kicked state in the right deck(s)
Feed the Swarm - some decks might care about this card's enchantment removal if their color restrictions lock them out of better options
Lithoform Blight - has issues at first glance, but it's important to remember it's 2 cmc, cantrips, and you can target opponent lands with it, including ones that aren't for color fixing but have abilities you don't want the opponent to have, or
Urza's Tower.
Mind Carver - could be situationally better than
Bone Saw, or
Paradise Mantle for quickly getting something equipped for some future deck
Nighthawk Scavenger - unfortunately, despite having something that resembles the goyf mechanic, it has too much holding it back, like 3 cmc, toughness just being set at 3, and not using all graveyards
Scourge of the Skyclaves - reminds me of
Death's Shadow such that I could see it seeing play
Skyclave Shade - there are better options, but it's still pretty strong, and might turn up when you need 5-8 of something similar
Soul Shatter - I could see this rarely popping up in sideboards
Cleansing Wildfire - I really wanted this to exist in Modern, and suspect it will see play.
Leyline Tyrant - This seems like it might do interesting things...
Roiling Vortex - This looks potentially useful, at least in sideboards
Valakut Exploration - One of the cheaper repeatable forms of this effect, and deals damage and puts it in the graveyard if the card isn't used
Wayward Guide-Beast - Probably isn't quite goblin-guide 5-8 but it still might be playable some places?
Ancient Greenwarden - already discussed a bit here
Cragplate Baloth - hexproof, haste, and can't be countered and it's bigger kicker form make me wonder about this as a ramp finisher in a sideboard against controlling decks, lack of trample or other evasion might be an issue though
Scale the Heights - look's somewhat Uro-like, but it's far from Uro
Scute Swarm - even if it's not competitive, I somewhat want to see a weird brew with exponential scutes! Maybe some weird backup win-con for scapeshift if Valakut has been hated out somehow?
Skyclave Pick-Axe - same as I mentioned above for Mind Carver
Swarm Shambler - seems like it might be useful somewhere that cares about +1/+1 counters
Grakmaw, Skyclave Ravager - replaces itself and plays with counters in an interesting way, maybe it'll find a place
Kaza, Roil Chaser - does storm want this? Baral and Electromancer are both wizards?
Linvala, Shield of Sea Gate - seems good for coco to stop removal or board-sweeps in certain situations, and maybe some hatebears lists
Yasharn, Implacable Earth - maybe some sideboards?
Cliffhaven Kitesail - see the black and green equipments above, plus this one grants evasion
Forsaken Monument - Tron trons tronly
Lithoform Engine - probably not, but so many copies!
Myriad Construct - I suspect something might want this at some point, even if it's only something like being a budget alternative to
Hangarback Walker for something that wants that
Utility Knife - Another one of these
Crawling Barrens - Something might want this manland
Emeria's Call - will almost never be cast in spell mode, but the land mode can enter untapped and it least it has the spell mode as an option late game
Kabira Takedown,
Sejiri Shelter - some of the better cards of this type in white, may see play where you want this kind of thing, perhaps wanting lands that don't count as lands in the library for searches or reveals, or the flexibility
Sea Gate Restoration - see Emeria's Call
Beyeen Veil,
Glasspool Mimic,
Jwari Disruption,
Silundi Vision - See white grouping
Agadeem's Awakening - See Emeria's Call, also might be relevant for it's self-damage in untapped land mode for Death's Shadow
Hagra Mauling,
Malakir Rebirth - See white grouping
Shatterskull Smashing - See Emeria's Call
Valakut Awakening - might be playable on it's own merits, but also see white grouping
Kazuul's Fury,
Spikefield Hazard - see white grouping
Turntimber Symbiosis - See Emeria's Call, but also note that green is the color of ramping
Bala Ged Recovery,
Kazandu Mammoth,
Khalni Ambush,
Tangled Florahedron,
Vastwood Fortification - see white grouping
Branchloft Pathway,
Brightclimb Pathway,
Clearwater Pathway,
Cragcrown Pathway,
Needleverge Pathway,
Riverglide Pathway - I could easily see these lands as being good enough for modern
