Primeval Protector

This spell costs {1} less to cast for each creature your opponents control.
When Primeval Protector enters, put a +1/+1 counter on each other creature you control.

Sproutback Trudge

This spell costs {X} less to cast, where X is the amount of life you gained this turn.
Trample
At the beginning of your end step, if you gained life this turn, you may cast Sproutback Trudge from your graveyard.

Kona, Rescue Beastie

Survival — At the beginning of your second main phase, if Kona, Rescue Beastie is tapped, you may put a permanent card from your hand onto the battlefield.

Rush of Knowledge

Draw cards equal to the highest mana value among permanents you control.

Ancient Ooze

Ancient Ooze's power and toughness are each equal to the total mana value of other creatures you control.

Thrasta, Tempest's Roar

This spell costs {3} less to cast for each other spell cast this turn.
Trample, haste
Trample over planeswalkers (This creature can deal excess combat damage to the controller of the planeswalker it's attacking.)
Thrasta, Tempest's Roar has hexproof as long as it entered this turn.

Shamanic Revelation

Draw a card for each creature you control.
Ferocious — You gain 4 life for each creature you control with power 4 or greater.

Lumbering Megasloth

This spell costs {1} less to cast for each counter among players and permanents.
Trample
Lumbering Megasloth enters tapped.

Boon of Boseiju

Target creature gets +X/+X until end of turn, where X is the greatest mana value among permanents you control. Untap it.

Khalni Hydra

This spell costs {G} less to cast for each green creature you control.
Trample

Octavia, Living Thesis

This spell costs {8} less to cast if you have eight or more instant and/or sorcery cards in your graveyard.
Ward {8}
Magecraft — Whenever you cast or copy an instant or sorcery spell, target creature has base power and toughness 8/8 until end of turn.

Energy Tap

Tap target untapped creature you control. If you do, add an amount of {C} equal to that creature's mana value.

Kiora, Behemoth Beckoner

Whenever a creature you control with power 4 or greater enters, draw a card.
−1: Untap target permanent.

Tolarian Terror

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)

Call of the Wild

{2}{G}{G}: Reveal the top card of your library. If it's a creature card, put it onto the battlefield. Otherwise, put it into your graveyard.

The Pride of Hull Clade

This spell costs {X} less to cast, where X is the total toughness of creatures you control.
Defender
{2}{U}{U}: Until end of turn, target creature you control gets +1/+0, gains "Whenever this creature deals combat damage to a player, draw cards equal to its toughness," and can attack as though it didn't have defender.

Rumbleweed

This spell costs {1} less to cast for each land card in your graveyard.
Vigilance, reach, trample
When Rumbleweed enters, other creatures you control get +3/+3 and gain trample until end of turn.

Outcaster Trailblazer

When Outcaster Trailblazer enters, add one mana of any color.
Whenever another creature you control with power 4 or greater enters, draw a card.
Plot {2}{G} (You may pay {2}{G} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Crashing Drawbridge

Defender
{T}: Creatures you control gain haste until end of turn.

Monkey Cage

When a creature enters, sacrifice Monkey Cage and create X 2/2 green Monkey creature tokens, where X is that creature's mana value.

Avatar of Might

If an opponent controls at least four more creatures than you, this spell costs {6} less to cast.
Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)

Sailors' Bane

This spell costs {1} less to cast for each card you own in exile and in your graveyard that's an instant card, a sorcery card, or a card that has an Adventure.
Ward {4} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {4}.)

Gate Colossus

This spell costs {1} less to cast for each Gate you control.
Gate Colossus can't be blocked by creatures with power 2 or less.
Whenever a Gate you control enters, you may put Gate Colossus from your graveyard on top of your library.

Metalwork Colossus

This spell costs {X} less to cast, where X is the total mana value of noncreature artifacts you control.
Sacrifice two artifacts: Return Metalwork Colossus from your graveyard to your hand.

Access Denied

Counter target spell. Create X 1/1 colorless Thopter artifact creature tokens with flying, where X is that spell's mana value.

Ghoultree

This spell costs {1} less to cast for each creature card in your graveyard.

Kavu Lair

Whenever a creature with power 4 or greater enters, its controller draws a card.

Defiler of Vigor

Trample
As an additional cost to cast green permanent spells, you may pay 2 life. Those spells cost {G} less to cast if you paid life this way. This effect reduces only the amount of green mana you pay.
Whenever you cast a green permanent spell, put a +1/+1 counter on each creature you control.

Ghalta, Primal Hunger

This spell costs {X} less to cast, where X is the total power of creatures you control.
Trample

Ancient Stone Idol

Flash
This spell costs {1} less to cast for each attacking creature.
Trample
When Ancient Stone Idol dies, create a 6/12 colorless Construct artifact creature token with trample.

Accelerated Mutation

Target creature gets +X/+X until end of turn, where X is the highest mana value among permanents you control.

Garruk's Uprising

When Garruk's Uprising enters, if you control a creature with power 4 or greater, draw a card.
Creatures you control have trample.
Whenever a creature you control with power 4 or greater enters, draw a card.

Thryx, the Sudden Storm

Flash
Flying
Spells you cast with mana value 5 or greater cost {1} less to cast and can't be countered.

Brine Giant

This spell costs {1} less to cast for each enchantment you control.

Aether Mutation

Return target creature to its owner's hand. Create X 1/1 green Saproling creature tokens, where X is that creature's mana value.

Towering Titan

Towering Titan enters with X +1/+1 counters on it, where X is the total toughness of other creatures you control.
Sacrifice a creature with defender: All creatures gain trample until end of turn.

Nyxborn Behemoth

This spell costs {X} less to cast, where X is the total mana value of noncreature enchantments you control.
Trample
{1}{G}, Sacrifice another enchantment: Nyxborn Behemoth gains indestructible until end of turn.

Goreclaw, Terror of Qal Sisma

Creature spells you cast with power 4 or greater cost {2} less to cast.
Whenever Goreclaw, Terror of Qal Sisma attacks, each creature you control with power 4 or greater gets +1/+1 and gains trample until end of turn.

Cryptic Serpent

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.