Flatline: Compares favorably to Mana Leak in an energy deck.
Forestsguy: This feels rather strong outside of an energy deck. I dread to imagine how broken it would be IN an energy deck.
Phyrexian Editor: Kind of wish the energy requirement scaled like the mana cost on Prototype Portal. Other than that, the flavor is lovely.
StonerKruphix: Certainly a strong finisher card, though I think it could be rare. On its own, it's generally worse than Overrun, but with energy...
Mergatroid_Jones: I feel like this would be printed at rare, but it is interesting. Curious to see if this is breakable.
Necarg: That's an RG giant that cares about energy alright. Seems fair
RyuumiGaroukuni: I like this angel. Honestly it could have been monowhite, but there's nothing wrong with it being WB
mirrislegend: Definitely an interesting option. Can produce massive amounts of energy, and let you recover some life if needed.
Observer of the Moon1UR
Creature - Human Wizard (U) T: Discard a card, then draw a card. If you discarded a card with converted mana cost seven or greater, draw a card. "Innistrad has been shaken to its core, and great powers of light and darkness have fallen. I forsee a time of growth in our future."
Each opponent exiles all token permanents he or she controls, then exiles a permanent he or she controls.
If an opponent controls no permanents, he or she loses the game.
Players take their upkeep steps, draw steps, main phases, combat steps, and end steps in any order you choose. "It seemed I will have made a grave error recently."
Initiate of the Evening Calm 2BB
Creature - Assassin (U)
When Initiate of the Evening Calm enters the battlefield, you may have it deal 1 damage to target creature.
Legacy 1B (1B, Exile this card from your graveyard: Target creature you control gains this card's abilities. Activate this ability only any time you could cast a sorcery.) “The night is meant to be dark, but never restless.”
IIW: Legacy <cost> (<cost>, Exile this card from your graveyard: Target creature you control gains this card's abilities. Activate this ability only any time you could cast a sorcery.)
Search target opponent’s library for X cards, half of which, rounded down, must be lands and the rest of which must be nonlands, and reveal them to that player. He or she shuffles his or her library, then puts those cards on top of his or her library in any order.
Creature - Human Rogue (U)
Whenever Generator Siphoner deals combat damage to a player, target land that player controls doesn't untap during its controller's next untap step and untap target land you control.
Boon of Dominaria's RebirthWUBRG
Put up to three target creature cards in your graveyard onto the battlefield under your control. Draw 3 cards. Put three black Rune artifact tokens onto the battlefield with "Sacrifice this artifact: Add B to your mana pool." Boon of Dominaria's Rebirth deals 3 damage to target creature or player. Put three +1/+1 counters on target creature you control, then you may have it fight another target creature.
IIW: A card that would make you everyone's target in a multiplayer game.
Last Stand is almost crying in a corner. Too good methinks.
Maelstrom of Five Suns5WUBRG
Target player loses 5 life, puts the top 25 cards of his or her library into his or her graveyard, and sacrifices all but five permanents he or she controls. You return up to five cards from your graveyard to your hand and draw five cards.
IIW: Make Clue-related cards in Black or red.
The "loses 5 life part" feels underwhelming, compared to the tremendous (or splashy, in the mills case) power of the other effects.
Spawn of ProgenitusXGG
Legendary Creature — Hydra (M)
Spawn of Progenitus enters the battlefield with a +1/+1 counter on it for each mana spent to cast it.
When you cast Spawn of Progenitus, if WWUUBBRRGG was spent to cast it, destroy all permanents.
IIW: "Destroy all..."
Destroy all other you mean? Still neat.
Next challenge: uneven/weird looking mana costs
Each player may return any number of permanent cards from his or her graveyard to the battlefield, then each player may cast any number of instant and/or sorcery cards from his or her graveyard without paying their mana cost.
Enchantment - Aura (C)
Enchanted creature gets +4/+4
Transience G(You may cast this for its transience cost. If you do, sacrifice the permanent it becomes at the beginning of your next upkeep.)
Enchantment - Aura (U)
When Star-Crossed Pair enters the battlefield, if it isn't a token, put a token copy of it onto the battlefield attached to target creature.
Whenever a creature enchanted by a card named Star-Crossed Pair dies, enchanted creature's controller sacrifices it. "Alas, to those in love, it can not be doomed, no matter the signs."
-Vadexei, star charter