Sheoldred, Whispering One

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
At the beginning of your upkeep, return target creature card from your graveyard to the battlefield.
At the beginning of each opponent's upkeep, that player sacrifices a creature of their choice.

Glacial Chasm

Cumulative upkeep—Pay 2 life. (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 this land enters, sacrifice a land.
Creatures you control can't attack.
Prevent all damage that would be dealt to you.

Lluwen, Imperfect Naturalist

When Lluwen enters, mill four cards, then you may put a creature or land card from among the milled cards on top of your library.
{2}{B/G}{B/G}{B/G}, {T}, Discard a land card: Create a 1/1 black and green Worm creature token for each land card in your graveyard.

Silvergill Mentor

As an additional cost to cast this spell, behold a Merfolk or pay {2}. (To behold a Merfolk, choose a Merfolk you control or reveal a Merfolk from your hand.)
When this creature enters, create a 1/1 white and blue Merfolk creature token.

Evershrike's Gift

Enchant creature
Enchanted creature gets +1/+0 and has flying.
{1}{W}, Blight 2: Return this card from your graveyard to your hand. Activate only as a sorcery. (To blight 2, put two -1/-1 counters on a creature you control.)

Eclipsed Realms

As this land enters, choose Elemental, Elf, Faerie, Giant, Goblin, Kithkin, Merfolk, or Treefolk.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a spell of the chosen type or activate an ability of a source of the chosen type.

Virulent Emissary

Deathtouch
Whenever another creature you control enters, you gain 1 life.

Champions of the Shoal

As an additional cost to cast this spell, behold a Merfolk and exile it. (Exile a Merfolk you control or a Merfolk card from your hand.)
Whenever this creature enters or becomes tapped, tap up to one target creature and put a stun counter on it.
When this creature leaves the battlefield, return the exiled card to its owner's hand.