Magdalena Bay enters tapped.
{T}: Add {G}, {W}, or {U}.
{VP}{VP}{VP}{VP}, Discard Magdalena Bay: Target creature gets +3/+3 and gains menace until end of turn.

Put a +1/+1 counter on target creature. It gets +0/+2 until end of turn.

Destroy target creature or planeswalker if it has mana value 3 or less or if you control a legendary creature.

Exile the top X cards of target opponent's library. You may play those cards for as long as they remain exiled, and you may pay {VP}{VP}{B} rather than pay the mana costs of those spells.

Each opponent separates the creatures they control into two piles. For each opponent, you choose one of their piles. Each opponent sacrifices the creatures in their chosen pile.

{2}, {T}: Exile target creature you control, then reveal the top card of your library. If the revealed card is a creature card, put it onto the battlefield. Otherwise, return the exiled card to the battlefield under its owner's control.

Until end of turn, target creature gets +2/+2 and gains trample and “Whenever this creature deals combat damage to a player, return target permanent card with mana value less than or equal to the damage dealt from your graveyard to your hand.”

Enchant land you control
Enchanted land is a 2/2 Elemental creature with vigilance, haste, and “{T}: Add two mana of different colors.” It's still a land.
If enchanted land would leave the battlefield, instead sacrifice Manifest the Lightveins and that land gains indestructible until end of turn.

Sacrifice a Treasure: Put a loyalty counter on Marilye, Dreaming Big.
[+1]: Draw a card, then discard a card. If you discarded a nonland card this way, create a tapped Treasure token.
[–3]: Gain control of target artifact. It becomes a Treasure artifact, loses all other types, and loses all abilities except for activated mana abilities.
[–8]: Target opponent chooses a nonland permanent they control. You gain control of the rest.

You lose life equal to the number of cards you've drawn this turn, then draw a card. You may repeat this process any number of times.

As an additional cost to cast this spell, sacrifice a creature.
Exile the top X cards of your library, where X is the sacrificed creature's power. Until the end of your next turn, you may play those cards.

Target creature you control gets +2/+1 until end of turn. It fights up to one target creature you don't control.

Choose a number between 0 and 5. Counter up to one target spell unless its controller pays {X}, where X is the chosen number. Then mill five minus X cards. You may return a card milled this way to your hand.

Target creature you control gets +2/+2 until end of turn. It fights target creature you don't control.

Target creature gains indestructible until end of turn. Teach it lifelink.

When Meeting of the Elites enters, create a tapped Treasure token.
You've sacrificed a nonland permanent this turn.

Create two 1/1 blue Wizard creature tokens with prowess.

Equipped creature gets +0/+1 and has vigilance.
Equipped creature assigns combat damage equal to its toughness rather than its power, and can attack as though it didn't have defender.
Equip {2}

Target artifact or creature's owner puts it on the top or bottom of their library.
Flashback {5}{U}{U}

Miasmic Cove enters tapped.
{T}: Add {B} or {G}.
{4}{B/G}: Miasmic Cove becomes a 2/3 black and green Snake creature with deathtouch until end of turn. It's still a land. This ability costs {X} less to activate, where X is your devotion to black and green. Activate only once each turn.

Exile the top three cards of your library. You may play up to two of those cards this turn.

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle. Then if you control three or more enchantments, draw a card.

Mirrormeld Spire has all abilities of land cards integrated onto permanents you control.
{T}: Add {C}.
{C}, {T}: Integrate the top card of target player's library.

Return target creature or enchantment to its owner's hand. If that permanent's controller has eight or more cards in their graveyard, its owner puts it on the top or bottom of their library instead.

Choose one. If your devotion to black is three or greater, you may choose another. The same is true for devotion to red.
• Create two tapped Treasure tokens.
• Creatures you control get +2/+0 until end of turn.
• Choose a nonland permanent type. Each opponent sacrifices a permanent of that type.