Mana Short

Tap all lands target player controls and that player loses all unspent mana.

Doubling Cube

{3}, {T}: Double the amount of each type of unspent mana you have.

Wall of Blossoms

Defender
When Wall of Blossoms enters the battlefield, draw a card.

Fastbond

You may play any number of lands on each of your turns.
Whenever you play a land, if it wasn't the first land you played this turn, Fastbond deals 1 damage to you.

Steel Wall

Overlaid Terrain

As Overlaid Terrain enters the battlefield, sacrifice all lands you control.
Lands you control have "{T}: Add two mana of any one color."

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Illusions of Grandeur

Cumulative upkeep {2} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
When Illusions of Grandeur enters the battlefield, you gain 20 life.
When Illusions of Grandeur leaves the battlefield, you lose 20 life.

Splendid Reclamation

Return all land cards from your graveyard to the battlefield tapped.

Braingeyser

Wall of Stone

Nyxbloom Ancient

Trample
If you tap a permanent for mana, it produces three times as much of that mana instead.

Force of Nature

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
At the beginning of your upkeep, Force of Nature deals 8 damage to you unless you pay {G}{G}{G}{G}.

Harmless Offering

Target opponent gains control of target permanent you control.

Island

Nissa, Worldwaker

+1: Target land you control becomes a 4/4 Elemental creature with trample. It's still a land.
+1: Untap up to four target Forests.
−7: Search your library for any number of basic land cards, put them onto the battlefield, then shuffle. Those lands become 4/4 Elemental creatures with trample. They're still lands.

Wall of Razors

Defender (This creature can't attack.)
First strike

Counterspell

Mountain

Omnath, Locus of Mana

You don't lose unspent green mana as steps and phases end.
Omnath, Locus of Mana gets +1/+1 for each unspent green mana you have.