Going through the submissions:
Enchantment Bringer is on one card in the same set. We should probably cut it.
Unshakable Resolve should cost
.
Sunchaser Procession should make 4 tokens. You aren't going to be able to attack with them until turn 5 at the earliest, so I think it needs more upside.
Apostle of Elori should be mythic. It's really complex.
Solar Flare doesn't need to be rare. It could be uncommon or even common.
Reification of Elori should be cheaper and have a better body. Maybe give it flying and cut the cost by 1?
Ethereal Form and Steam Cloak are similar enough that they probably shouldn't be in the same set.
Mist Weaver: change it to a "whenever an enchantment enters the battlefield under your control" trigger, and make it an enchantment creature.
Snowblind Haint: No p/t
Frostblight Foresight: Make it dependent on the number of artifacts you control so that it will work with relics, and make it x+1 so that you can always cycle it.
Spellbound Serpent: should be common.
Wall of Cloud: unplayably bad. Make it return to its owner's hand every upkeep instead of saccing?
Cheapshot Enthusiast: should be 2/1.
Instruments of Torture: maybe change it to an aura with the relic as an etb trigger?
Irondeep Spelunker: maybe make it artifact or creature, so you can sac a relic?
Shamebearer: I think this would be better if it triggered on your enchantments than your opponent's, so that you can build around it instead of siding it in.
Icy Whisper: really weak. At best it lets you spend a card and 2 mana to get a 2 mana spell, and at worst it's an awkwardly costed card that does nothing if you don't have any instants in your 'yard. I think it would be better if it cost
, cantripped, and could hit sorceries too.
Eater of Dreams: needs p/t. Fun fact: WOTC tries to make 6cmc demons 6/6s. MaRo actually said it in a podcast.
Lich of Lost Treasures: to avoid confusion, we should specify that you exile the cards from a graveyard. I was showing the set to a buddy of mine and he thought it exiled cards from the board.
Gravefall: I thought unconditional removal was supposed to cost
?
Magespark Elemental: Most cards with this effect have trample, and I see no reason why this one shouldn't too.
Raid the Ruins: there's pretty much no reason to cast this instead of engraving it. Maybe make it a sorcery that costs
?
Sparksigil Apprentice: there is a grand total of 2 red sorceries in the set. I think this should be able to hit instants too, so that it isn't so narrow.
Grove Tender: By the time you have mastery, you really don't care about them using removal on your mana dork. I think the card would be cleaner if you just took off the mastery hexproof.
Tank Golem: getting enough artifacts into play to actually kill someone with this is a daunting task. How about "Tap another untapped artifact you control: untap ~"?
Weathered Cloak: this card has memory issues, and protection isn't usually used at common anymore because it's hard for newer players to understand. I think this should be bumped up to uncommon.
Icecore Golem: needs p/t.
Shatterspear Insignia: I think this card could afford to reduce costs by
.
Mox Amber: a mana source that doesn't make any mana until you already have a bunch of stuff out doesn't need to be legendary.
Spires: maybe make this a cycle? Black gets back instants, red gets back sorceries, and green gets back creatures?