Freeborn Sailors -- 1RR
Creature - Human Pirate
Other players can't gain control of Freeborn Sailors.
, : Gain control of target permanent you own.
2/3
Adventurous Buccaneer -- 1RB
Creature - Pirate
Whenever Adventurous Buccaneer attacks, explore. If an instant or sorcery card is revealed this way, exile it. Until the end of the next turn, you may cast it as though it had flash.
1/3
"Until end of turn, each creature's power and toughness becomes equal to its base power and toughness." Note that this has some unexpected interactions with cards like Turn to Frog, About Face, and a few other types of cards.'
Darkening Frost -- It's a nice combination of effects. I'm surprised it hasn't been done before!
It needs to be 2UU. That's the same cost as Control Magic (and that's an o-l-d card), which gains control of the creature immediately, but has the drawback of being disenchantable. Even if you don't get use of the creature immediately, you're still robbing your opponent of its use. Plus, blue has all sorts of untap shenanigans, or it could be sacrificed to pay for some bigger ability.
.
Pride of Leadership -- 2WW
Enchantment - Aura
Enchant creature
Whenever enchanted creature deals combat damage to a player, its controller creates that many 1/1 white Follower creatures.
When enchanted creature dies, exile all Followers.
Vicious Raptor -- 2RG
Creature - Dinosaur
Whenever Vicious Raptor fights another creature, put a +1/+1 counter on it. RG: Vicious Raptor fights target creature you control with lower toughness than Vicious Raptor's power.
3/3
Stalking Raptor -- 1WG
Creature - Dinosaur
Flash
Stalking Raptor has first strike as long as you control a Plains.
Stalking Raptor has trample as long as you control a Forest.
As long as you control a Forest and a Plains, STalking Raptor gets +1/+1.
2/3
If it had a higher mana cost itself, it m-i-g-h-t be acceptable. It would have more interest for me if it made the mana payment required; i.e., you can no longer pay energy but have to pay (2) instead. And for all players.
Maw of Damnation -- 5BR
Creature - Dinosaur
Trample
Whenever a creature dies, if Maw of Damnation dealt damage to it this turn, exile it instead.
Maw of Damnation gets +1/+1 for each creature exiled by it.
7/7
Natural Beauty -- 2WG
Enchantment - Aura
Enchant creature or player
Enchanted creature gains hexproof and can't be blocked.
Enchanted player gains hexproof and spells he or she casts can't be countered.
Herald of Hope -- Definitely needs some flavor to explain how a hydra (a fearsome and feared creature) is viewed as a herald. The third ability is a little confusing; what does "it" at the end of the ability refer to -- the hydra, or the source (...or possibly the creature it's shielding?)
It might be simpler to reduce the last ability to its lowest common denominator -- "1, remove a +1/+1 counter ... prevent the next 1 damage" You can still prevent greater sums of damage by activating the ability multiple times.
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Lord Ichibarra's Timepiece -- 3
Artifact
At the end of each turn, untap the last permanent you control that became tapped that turn.
Frostblown Cryosaur -- 3WW
Snow Creature - Dinosaur
Frostblown Cryosaur gets +1/+0 for each other snow permanent you control.
As long as you control three or more snow lands, Frostblown Cryosaur has vigilance and first strike.
3/3
Aven Interdictor doesn't have much interaction with storm; storm copies the spells directly, rather than requiring the player to cast them.
Forger of Blights makes flavor-sense in Phyrexia, but not elsewhere. It's interesting that a many Germs will die immediately (Lightning Greaves and so many others that don't offer a toughness boost.) It still seems weird for a white card to create black tokens.
Lash Out -- 2R
Enchantment - Aura
Enchant creature
At the beginning of enchanted creature's upkeep, enchanted creature fights a random target creature.
Enchanted creature must attack each turn if able. "I just wanted to punch somebody in the face, with all the strength and anger built up inside me...."
Yawgmoth's Colossus -- 8
Artifact Creature - Giant
As Yawgmoth's Colossus enters the battlefield, sacrifice all other creatures you control. For each creature sacrificed this way, Yawgmoth's Titan enters play with an additional +1/+1 counter on it.
As long as Yawgmoth's Colossus has eight or more +1/+1 counters on it, it has haste, trample and menace.
8/8
Creature - Human Pirate
Other players can't gain control of Freeborn Sailors.
, : Gain control of target permanent you own.
2/3
Creature - Human Pirate
Distrustful Lackey can't crew Vehicles.
Equipment can't equip Distrustful Lackey.
3/1
Creature - Pirate
Whenever Adventurous Buccaneer attacks, explore. If an instant or sorcery card is revealed this way, exile it. Until the end of the next turn, you may cast it as though it had flash.
1/3
Creature - Dinosaur
Flying
: Target creature gains flying and gets +4/+2 until Xolotl's Steed becomes untapped.
4/2
It needs to be 2UU. That's the same cost as Control Magic (and that's an o-l-d card), which gains control of the creature immediately, but has the drawback of being disenchantable. Even if you don't get use of the creature immediately, you're still robbing your opponent of its use. Plus, blue has all sorts of untap shenanigans, or it could be sacrificed to pay for some bigger ability.
.
Pride of Leadership -- 2WW
Enchantment - Aura
Enchant creature
Whenever enchanted creature deals combat damage to a player, its controller creates that many 1/1 white Follower creatures.
When enchanted creature dies, exile all Followers.
Creature - Dinosaur
Whenever Vicious Raptor fights another creature, put a +1/+1 counter on it.
RG: Vicious Raptor fights target creature you control with lower toughness than Vicious Raptor's power.
3/3
Creature - Dinosaur
Flash
Stalking Raptor has first strike as long as you control a Plains.
Stalking Raptor has trample as long as you control a Forest.
As long as you control a Forest and a Plains, STalking Raptor gets +1/+1.
2/3
Creature - Dinosaur
Trample
Whenever a creature dies, if Maw of Damnation dealt damage to it this turn, exile it instead.
Maw of Damnation gets +1/+1 for each creature exiled by it.
7/7
Enchantment - Aura
Enchant creature or player
Enchanted creature gains hexproof and can't be blocked.
Enchanted player gains hexproof and spells he or she casts can't be countered.
It might be simpler to reduce the last ability to its lowest common denominator -- "1, remove a +1/+1 counter ... prevent the next 1 damage" You can still prevent greater sums of damage by activating the ability multiple times.
.
Lord Ichibarra's Timepiece -- 3
Artifact
At the end of each turn, untap the last permanent you control that became tapped that turn.
Snow Creature - Dinosaur
Frostblown Cryosaur gets +1/+0 for each other snow permanent you control.
As long as you control three or more snow lands, Frostblown Cryosaur has vigilance and first strike.
3/3
Forger of Blights makes flavor-sense in Phyrexia, but not elsewhere. It's interesting that a many Germs will die immediately (Lightning Greaves and so many others that don't offer a toughness boost.) It still seems weird for a white card to create black tokens.
Lash Out -- 2R
Enchantment - Aura
Enchant creature
At the beginning of enchanted creature's upkeep, enchanted creature fights a random target creature.
Enchanted creature must attack each turn if able.
"I just wanted to punch somebody in the face, with all the strength and anger built up inside me...."
Artifact Creature - Giant
As Yawgmoth's Colossus enters the battlefield, sacrifice all other creatures you control. For each creature sacrificed this way, Yawgmoth's Titan enters play with an additional +1/+1 counter on it.
As long as Yawgmoth's Colossus has eight or more +1/+1 counters on it, it has haste, trample and menace.
8/8