Temple of Hungry Gods
Land T: Add 1 to your mana pool. 7, T: Choose target permanent. At the beginning of your next upkeep, sacrifice Temple of Hungry Gods. If you do, destroy that permanent. Activate this ability as a sorcery.
Roaming Atoll
Land
Roaming Atoll enters the battlefield tapped.
Whenever you cast a spell for the first time during an opponents turn, you may pay 1 life. If you do, untap Roaming Atoll. T: Add U to your mana pool.
Gleaming Beacon
Land - Beacon
When Gleaming Beacon enters the battlefield, each opponent puts a Beacon land token onto the battlefield with, "T: Add one mana of any color to your mana pool." T: Add one mana of any color to your mana pool.
Chicken-Leg Cottage
Land T: Add B to your mana pool. Spend this mana only to cast spells that target one or more creatures.
Whenever a spell paid for with mana from Chicken-Leg Cottage destroys a creature, Chicken-Leg Cottage loses all abilities and becomes a 4/4 black Construct artifact creature.
Gravity Falls
Land T: Add RR to your mana pool. At the beginning of your next upkeep, you lose the game unless you pay R.
Temple of Hungry Gods: Seems fine. Would be good in EDH.
Roaming Atoll: This is OP. You should probably only make it tap for colorless, or make it only spendable on instant spells.
Gleaming Beacon: I dunno if this would be playable or not, but it's not OP or anything.
Chicken-Leg Cottage: Should probably enter the battlefield tapped. The design is kind of awkward, should probably make it into a flip card or sac the land and create a 4/4 token.
Gravity Falls: Should ETB tapped.
Roaming Atoll: Being able to untap it like that is too strong. The cost would need to skyrocket to 3-4 life to be balanced.
Gleaming Beacon: This is really interesting. Giving your opponent a copy of your land is an odd drawback, and i really like this.
Chicken-Leg Cottage: Making the land into a permanent 4/4 that can still tap for mana is a bit strong. Casting a kill spell isn't tough in black. Maybe a 4/2 or a 3/3.
Gravity Falls: So, it gives you a huge boost in RDW, then it becomes a Mountain? Probably too strong.
Dahammer4
Artifact - Equipment (R)
Choose one - Equipped creature gets +4/+0; or Double Strike; or "When this creature deals combat damage to a creature, exile that creature"; or t, unattach ~ from this creature: ~ deals 5 damage to target creature." t: Equipped creature gains flying until end of turn.
Equip 3
Land
T: Add 1 to your mana pool.
7, T: Choose target permanent. At the beginning of your next upkeep, sacrifice Temple of Hungry Gods. If you do, destroy that permanent. Activate this ability as a sorcery.
Roaming Atoll
Land
Roaming Atoll enters the battlefield tapped.
Whenever you cast a spell for the first time during an opponents turn, you may pay 1 life. If you do, untap Roaming Atoll.
T: Add U to your mana pool.
Gleaming Beacon
Land - Beacon
When Gleaming Beacon enters the battlefield, each opponent puts a Beacon land token onto the battlefield with, "T: Add one mana of any color to your mana pool."
T: Add one mana of any color to your mana pool.
Chicken-Leg Cottage
Land
T: Add B to your mana pool. Spend this mana only to cast spells that target one or more creatures.
Whenever a spell paid for with mana from Chicken-Leg Cottage destroys a creature, Chicken-Leg Cottage loses all abilities and becomes a 4/4 black Construct artifact creature.
Gravity Falls
Land
T: Add RR to your mana pool. At the beginning of your next upkeep, you lose the game unless you pay R.
Banner by Topher!
Roaming Atoll: This is OP. You should probably only make it tap for colorless, or make it only spendable on instant spells.
Gleaming Beacon: I dunno if this would be playable or not, but it's not OP or anything.
Chicken-Leg Cottage: Should probably enter the battlefield tapped. The design is kind of awkward, should probably make it into a flip card or sac the land and create a 4/4 token.
Gravity Falls: Should ETB tapped.
Modern
UBR Grixis Control
U Merfolk
Pauper
U Mono U Delver
Ancestral Visions is freed
Temple of Hungry Gods - Curious delayed trigger, but sure, I like it.
Roaming Atoll - Danger! This is definitely a card to flag and follow closely as it's play-tested.
Gleaming Beacon - Sure! I could imagine seeing a variant of this in a Return to Zendikar block, except it gives each opponent an Eldrazi Spawn token.
Chicken-Leg Cottage - This doesn't feel like a land at all. It would be better as an artifact, so that it doesn't disrupt your land drops.
Gravity Falls - Haha another card to watch out for. Still, I'm very curious to see it played.
Custom Card / Set Reviewer
When reviewing custom cards / sets, I look for (a) flavour, (b) function, and (c) cohesiveness, generally through a risk focus.
Gleaming Beacon: This is really interesting. Giving your opponent a copy of your land is an odd drawback, and i really like this.
Chicken-Leg Cottage: Making the land into a permanent 4/4 that can still tap for mana is a bit strong. Casting a kill spell isn't tough in black. Maybe a 4/2 or a 3/3.
Gravity Falls: So, it gives you a huge boost in RDW, then it becomes a Mountain? Probably too strong.
Sigpic by Rivenor
Artifact - Equipment (R)
Choose one - Equipped creature gets +4/+0; or Double Strike; or "When this creature deals combat damage to a creature, exile that creature"; or t, unattach ~ from this creature: ~ deals 5 damage to target creature."
t: Equipped creature gains flying until end of turn.
Equip 3
Courtesy of Crepes
[OMC] Omerium's Collapse