Decomposition

Enchant black creature
Enchanted creature has "Cumulative upkeep—Pay 1 life." (At the beginning of its controller's upkeep, that player puts an age counter on it, then sacrifices it unless they pay its upkeep cost for each age counter on it.)
When enchanted creature dies, its controller loses 2 life.

Freyalise's Charm

Whenever an opponent casts a black spell, you may pay {G}{G}. If you do, you draw a card.
{G}{G}: Return Freyalise's Charm to its owner's hand.

Ice Storm

Barbed Sextant

{1}, {T}, Sacrifice Barbed Sextant: Add one mana of any color. Draw a card at the beginning of the next turn's upkeep.

Pendelhaven

{T}: Add {G}.
{T}: Target 1/1 creature gets +1/+2 until end of turn.

Grizzly Bears

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Urza's Bauble

{T}, Sacrifice Urza's Bauble: Look at a card at random in target player's hand. You draw a card at the beginning of the next turn's upkeep.

Hurricane

Hurricane deals X damage to each creature with flying and each player.

Balduvian Bears

Rambling Possum

Whenever Rambling Possum attacks while saddled, it gets +1/+2 until end of turn. Then you may return any number of creatures that saddled it this turn to their owner's hand.
Saddle 1 (Tap any number of other creatures you control with total power 1 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)

Crumble

Destroy target artifact. It can't be regenerated. That artifact's controller gains life equal to its mana value.

Prevent all combat damage that would be dealt this turn.

Spectral Bears

Whenever Spectral Bears attacks, if defending player controls no black nontoken permanents, it doesn't untap during your next untap step.

Undergrowth

As an additional cost to cast this spell, you may pay {2}{R}.
Prevent all combat damage that would be dealt this turn. If this spell's additional cost was paid, this effect doesn't affect combat damage that would be dealt by red creatures.

Sylvan Library

At the beginning of your draw step, you may draw two additional cards. If you do, choose two cards in your hand drawn this turn. For each of those cards, pay 4 life or put the card on top of your library.

Wall of Ice

Forest

Pygmy Allosaurus

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)

Darksteel Colossus

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Indestructible (Damage and effects that say "destroy" don't destroy this creature.)
If Darksteel Colossus would be put into a graveyard from anywhere, reveal Darksteel Colossus and shuffle it into its owner's library instead.

Llanowar Elves

Tsunami

Untamed Wilds

Search your library for a basic land card, put that card onto the battlefield, then shuffle.

Hollow Trees

Hollow Trees enters tapped.
You may choose not to untap Hollow Trees during your untap step.
At the beginning of your upkeep, if Hollow Trees is tapped, put a storage counter on it.
{T}, Remove any number of storage counters from Hollow Trees: Add {G} for each storage counter removed this way.

Kaysa

Tranquility

Whirling Dervish

Protection from black
At the beginning of each end step, if Whirling Dervish dealt damage to an opponent this turn, put a +1/+1 counter on it.

Black Lotus

{T}, Sacrifice Black Lotus: Add three mana of any one color.

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Copper Tablet

At the beginning of each player's upkeep, Copper Tablet deals 1 damage to that player.

Craw Giant

Trample
Rampage 2 (Whenever this creature becomes blocked, it gets +2/+2 until end of turn for each creature blocking it beyond the first.)