Machinarium
Legendary Land
:symtap:, Pay 1 life: Put a 1/1 colorless Drone artifact creature token onto the battlefield. It has "Sacrifice this creature: Add to your mana pool." "Someday you may find yourself surrounded by the monotonous beauty of Drones."
-Ed, Endless Engineer
The name is a tribute to a fantastic little game by some Czech game developers. The card has little other connection to the game though.
If your opponent can't deal with it, you have the option to trade 12 life for about 11.
Since it has haste, actually it can ball lightning and you could sacrifice it before having to pay the life. Or you could deal about 11 and take 6... but it is a risk since your opponent gets a whole turn to do something about it.
Ball Fire :symr::symr::symr:
Creature - Elemental
Haste, Trample, Lose 6 life at the beginning of the end step.
Sacrifice Ball Fire: Ball Fire deals 1 damage to target player.
Sacrifice Ball Fire: Ball Fire deals 2 damage to target creature.
Sacrifice Ball Fire: Ball Fire deals 3 damage to all attacking and blocking creatures.
5/1
Decomposers :2mana::symb::symb:
Enchantment (U)
At the beginning of your upkeep, you may exile a creature card in any graveyard from the game. If you do, put a 1/1 black Insect creature token with flying onto the battlefield. "There is nothing sinister about these creatures, but Lord Axlore's daily executions seem superfluous in maintaining their survival." -Lord Axlore's late biological adviser.
Keyword - Inflict 1 - players lose 1 life for each spell they cast this turn.
Thrull Broodsong :3mana::symb:
Sorcery
Affinity for Thrulls.
Put two black 1/1 Thrull counters onto the battlefield. Until the end of turn, Thrull spells you cast cost less for each Thrull you control.
Inflict 1 (A player loses 1 life whenever that player casts a spell this turn.)
Skittle :symu::symr::symg:
Sorcery
Target permanent is blue, red, and green. Draw a card.
Put a blue, red, or green counter on each permanent that shares converted mana cost with the targeted permanent.
Permanents with color counters have ":symtap:: Add one mana of any color of counter on this permanent to your mana pool." Taste the rainbow.
Thought Drones :2mana::symu:
Instant
Put a 1/1 blue Drone Creature token onto the battlefield and draw a card.
Whenever a player casts a spell with converted mana cost equal to the number of cards named Thought Drones in your graveyard, you may return a card named Though Drones to your hand.
I. :3mana::symu::symu:
H. Tribal Instant - Elemental
C. Feedback - Until end of turn, spells deal damage to their controller equal to those spells' converted mana cost.
H. N/A (card is not a creature).
Charged Wind :3mana::symu::symu:
Tribal Instant - Elemental
You may pay five life rather than pay Charged Wind's mana cost.
You may counter target spell.
Feedback - Until end of turn, other spells deal damage to their controller equal to those spells' converted mana cost.
Until end of turn, players may pay rather than pay a spell's mana cost. "It like getting the energy of a five hour energy potion packed into five seconds."
-Wind Wizard
9/10 Very Cool effects for Doomtroll. I'd love to see the art for those guys.
Solemn Solitude
Sorcery
As an additional cost to cast Solemn Solitude put a +1/+1 counter on each of target opponent's creatures. Target creature gets -X/-X where X is equal to the number of +1/+1 counters put on creatures this way. At the beginning of your end step you may pay Y life and remove Y +1/+1 counters from creatures. "I'm so damn lonely."
-Isolated One
Dungeon :2mana::symb:
Instant
Destroy target creature. If it is put into the graveyard, its controller puts a token copy of it with defender into play.
// Dragon :1mana::symur::symur:
Instant
Put a blue red 4/4 dragon token into play with flying. Sacrifice it at the end of the combat step.
Giant Dwarf Ninja :2mana::symr::symb:
Creature - Giant Dwarf Ninja
Ninjitsu :symrb::symbr:
Whenever Giant Dwarf Ninja deals combat damage to a player, search your library for a Dwarf, Giant, or Ninja card and reveal that card to all players. Put that card into your hand and shuffle your library. So wrong, yet so right.
4/3
Ferment :1mana::symbg:
Instant
If was spent to cast Ferment, you may destroy target green creature. If was spent to cast Ferment, you may put two +1/+1 counters on target green creature.
If :symb::symg: was spent to cast Ferment, choose one- do both; or destroy target non-artifact creature at the beginning of the end step. Some things improve with time, other things just rot.
oops fit into blue!
Simianize :3mana::symbg:
Instant
If was spent to cast Simianize, you may destroy target creature. It can't be regenerated.
If was spent to cast Simianize, put a 3/3 green Ape creature token onto the battlefield.
If no green was spent to cast Simianize, that creature's controller puts a 3/3 green Ape creature token onto the battlefield. After the Dark Lord Gath was inadvertently pongified by one of his minions, he felt compelled to improve the spell.
Nap :1mana::symu:
Instant (c)
Draw a card. Target creature becomes blue until end of turn.
Choose one— tap that creature; or that creature gets -3/-0 until end of turn.
Flashback—:1mana::symu:, Pay 2 life.
Legendary Land
:symtap:, Pay 1 life: Put a 1/1 colorless Drone artifact creature token onto the battlefield. It has "Sacrifice this creature: Add
"Someday you may find yourself surrounded by the monotonous beauty of Drones."
-Ed, Endless Engineer
Since it has haste, actually it can ball lightning and you could sacrifice it before having to pay the life. Or you could deal about 11 and take 6... but it is a risk since your opponent gets a whole turn to do something about it.
Creature - Elemental
Haste, Trample, Lose 6 life at the beginning of the end step.
Sacrifice Ball Fire: Ball Fire deals 1 damage to target player.
Sacrifice Ball Fire: Ball Fire deals 2 damage to target creature.
Sacrifice Ball Fire: Ball Fire deals 3 damage to all attacking and blocking creatures.
5/1
Enchantment (U)
At the beginning of your upkeep, you may exile a creature card in any graveyard from the game. If you do, put a 1/1 black Insect creature token with flying onto the battlefield.
"There is nothing sinister about these creatures, but Lord Axlore's daily executions seem superfluous in maintaining their survival."
-Lord Axlore's late biological adviser.
Thrull Broodsong :3mana::symb:
Sorcery
Affinity for Thrulls.
Put two black 1/1 Thrull counters onto the battlefield. Until the end of turn, Thrull spells you cast cost
Inflict 1 (A player loses 1 life whenever that player casts a spell this turn.)
Sorcery
Target permanent is blue, red, and green. Draw a card.
Put a blue, red, or green counter on each permanent that shares converted mana cost with the targeted permanent.
Permanents with color counters have ":symtap:: Add one mana of any color of counter on this permanent to your mana pool."
Taste the rainbow.
Instant
Put a 1/1 blue Drone Creature token onto the battlefield and draw a card.
Whenever a player casts a spell with converted mana cost equal to the number of cards named Thought Drones in your graveyard, you may return a card named Though Drones to your hand.
H. Tribal Instant - Elemental
C. Feedback - Until end of turn, spells deal damage to their controller equal to those spells' converted mana cost.
H. N/A (card is not a creature).
Charged Wind :3mana::symu::symu:
Tribal Instant - Elemental
You may pay five life rather than pay Charged Wind's mana cost.
You may counter target spell.
Feedback - Until end of turn, other spells deal damage to their controller equal to those spells' converted mana cost.
Until end of turn, players may pay
"It like getting the energy of a five hour energy potion packed into five seconds."
-Wind Wizard
Solemn Solitude
Sorcery
As an additional cost to cast Solemn Solitude put a +1/+1 counter on each of target opponent's creatures. Target creature gets -X/-X where X is equal to the number of +1/+1 counters put on creatures this way. At the beginning of your end step you may pay Y life and remove Y +1/+1 counters from creatures.
"I'm so damn lonely."
-Isolated One
Make a card that represents discomfort
Instant
Destroy target creature. If it is put into the graveyard, its controller puts a token copy of it with defender into play.
//
Dragon :1mana::symur::symur:
Instant
Put a blue red 4/4 dragon token into play with flying. Sacrifice it at the end of the combat step.
Creature - Giant Dwarf Ninja
Ninjitsu :symrb::symbr:
Whenever Giant Dwarf Ninja deals combat damage to a player, search your library for a Dwarf, Giant, or Ninja card and reveal that card to all players. Put that card into your hand and shuffle your library.
So wrong, yet so right.
4/3
The art would be something like this lead figure:
Or loosely based on this guy:
just kidding
Ferment :1mana::symbg:
was spent to cast Ferment, you may destroy target green creature. If 
was spent to cast Ferment, you may put two +1/+1 counters on target green creature. Instant
If
If :symb::symg: was spent to cast Ferment, choose one- do both; or destroy target non-artifact creature at the beginning of the end step.
Some things improve with time, other things just rot.
oops fit into blue!
Simianize :3mana::symbg:
Instant
If
If
If no green was spent to cast Simianize, that creature's controller puts a 3/3 green Ape creature token onto the battlefield.
After the Dark Lord Gath was inadvertently pongified by one of his minions, he felt compelled to improve the spell.
Instant (c)
Draw a card. Target creature becomes blue until end of turn.
Choose one— tap that creature; or that creature gets -3/-0 until end of turn.
Flashback—:1mana::symu:, Pay 2 life.