The "I Like You" Game

[spacemonaut]

Nyx-Touched Bear 1G
Enchantment Creature — Bear
2/2
Trample
Bestow 2G (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
Enchanted creature gets +2/+2 and has trample.

[Henlock]

Iaro, Storyteller of Bravia wg
legendary Creature - Human Druid (r)
Creature spells you cast cost less.
Enchantment spells you cast cost less.
2/2

[Krishnath]

Talon of Nylea
2GG
Enchantment Creature - Cat (Rare)
Trample
Talon of Nylea can't be blocked by more than one creature.
4/4

[void_nothing]

Arahbo's Response W
Instant
Choose one -
• Untap target creature you control. It gets +2/+2 until end of turn.
• Untap all Cat creatures you control. They get +1/+1 until end of turn.

[Krishnath]

Arahbo's Charm
WG
Instant (Uncommon)
Chose one —
• Create two 1/1 white Cat creature tokens with lifelink.
• Target creature gets +2/+2 and gains trample until end of turn.
• Creatures you control gain vigilance until end of turn.

[spacemonaut]

Power Overwhelming RGG
Enchantment — Aura (Mythic Rare)
Enchant creature
If a spell or ability would increase the power or toughness of enchanted creature, it increases that creature's power or toughness by twice that much instead.

(Gatherer rulings would include this one: +1/+1 counters remain unaffected. Their power and toughness boost is granted by the rules, not by a spell or ability.)

[void_nothing]

Molten Thrust R
Sorcery
As an additional cost to cast this spell, sacrifice an artifact.
Target creature gets +6/+0 until end of turn.
Cycling W
"Five of the finest blades found their temper in enemy chests before the great smith had the time to finish Revolaire." - Romance of Ancient Voldane

[Krishnath]

Oketra's Presence
1W
Enchantment (Rare)
Whenever you cycle or discard a card, you gain 1 life.
Cycling 3W
When you cycle Oketra's Presence, you may search your library for a plains or desert land card, reveal it and put it into your hand. Then shuffle your library.

[void_nothing]

Ujmad's Hell, Isle of Lost Thought
Legendary Land - Desert Island
(T: Add U.)
Whenever Ujmad's Hell becomes tapped, it deals 2 damage to you.
Other Deserts you control have hexproof.
XU, T, Exile an instant or sorcery card with converted mana cost X from your graveyard, Sacrifice Ujmad's Hell: Draw X cards. Activate this ability only if you've cast an instant spell and a sorcery spell this turn.

[spacemonaut]

Kess's Recital {U/B}R
Instant
You may cast target sorcery card in a graveyard this turn.

[Krishnath]

Sphinx's Tutelage
2U
Enchantment (Rare)
Whenever you cast a spell from your graveyard, you may draw a card.

[void_nothing]

Bad luck of a twofer Wizards-beat-you-to-it there. Sphinx's Tutelage is already a card name and Secrets of the Dead is a nearly functionally identical card.

Memory of the Harvest 1G
Instant
Discard a land card. If you do, until end of turn, whenever you tap a land for mana, add an additional one mana of any type the discarded card could produce.
Flashback 1G

[spacemonaut]

I think Memory of the Harvest might actually not work in the rules: lands not on the battlefield usually can't produce mana at all. But we know what you mean. And then again, what if they could..?

Overgrown Foothills
Land
Overgrown Foothills enters the battlefield tapped.
T: Add R or G.
1, Exile Overgrown Foothills from your graveyard: Add RG.

[Henlock]

Dig
Instant (c)
Buyback-- Sacrifice a land.
Add one mana of any color.

[Krishnath]

Dig is a terrible card, but...

Lich's Realm
2BB
Enchantment (R)
Skeleton creatures you control get +1/+1.
Whenever you sacrifice a nontoken permanent, you may draw a card.

Dammit about Sphinx's tutelage though. >.<

[spacemonaut]

Lich's Realm is beautiful for Lich effects! Liches are typed as Zombies, but let's work with that...

Lich of the Citadel 2BBB
Creature — Zombie Wizard (R)
3/3
Deathtouch
When ~ enters the battlefield, create two 1/1 black Skeleton Warrior creature tokens.
If you would be dealt damage, prevent that damage and sacrifice that many permanents.
1B: Create a 1/1 black Skeleton Warrior creature token.

[Henlock]

Dig is a terrible card, but...

Storm!

Mating Season
Sorcery (r)
Convoke
Populate X times.

[Krishnath]

Boros Champion
2RRWW
Creature - Human Soldier (Rare)
Vigilance, First Strike, Trample,
Boros Champion's power and toughness are each equal to the number of creatures you control.
*/*

[Henlock]

Inner-wild Inspiriter 2gg
Creature - Elemental Avatar (r)
The base power and toughness of each creature you control are each equal to that creature's converted mana cost.
4/4

[void_nothing]

Prototype Timesucker
Artifact Creature - Leviathan
Flying, trample
Whenever Prototype Timesucker deals combat damage to a player, you may exile it. If you do, that player skips their next two turns.
Memnarch did not loose the eaters of days on Mirrodin without testing.
4/3

[Flatline]

Platinum Myr 4
Artifact Creature — Myr
t: Add c for each artifact you control.
2/3

[Krishnath]

Spoils of Conquest
2RR
Sorcery (Uncommon)
Each opponent sacrifices an artifact or a nonbasic land. Create a treasure token for each permanent sacrificed in this way (Treasure tokens are artifacts with "T, Sacrifice this artifact: Add one mana of any color.")

[void_nothing]

Ezuri's Dismantling 1G
Enchantment
When Ezuri's Dismantling enters the battlefield, each opponent creates a 3/3 colorless Golem artifact creature token.
Whenever a Golem leaves the battlefield, you gain 2 life and draw two cards.

[Flatline]

Fear Splicer 3b
Creature — Human Artificer
When Fear Splicer enters the battlefield, create a 3/3 colorless Golem artifact creature token.
Golem creatures you control have menace.
1/1

[Krishnath]

Crafter's Codex
4
Artifact (Rare)
Artificer creatures and artifacts you cast cost 1 less to cast.
Whenever an artifact creature enters the battlefield under your control, you may put a +1/+1 counter on it.
Whenever a noncreature artifact enters the battlefield under your control, you may put a charge counter on it.