Archdemon of Unx

Flying, trample
At the beginning of your upkeep, sacrifice a non-Zombie creature, then create a 2/2 black Zombie creature token.

Herald of Leshrac

Flying
Cumulative upkeep—Gain control of a land you don't control. (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.)
Herald of Leshrac gets +1/+1 for each land you control but don't own.
When Herald of Leshrac leaves the battlefield, each player gains control of each land they own that you control.

Heavyweight Demolisher

Menace
At the beginning of your upkeep, tap Heavyweight Demolisher unless you pay {3}.
Unearth {6}{R}{R} ({6}{R}{R}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Wormfang Manta

Flying
When Wormfang Manta enters, you skip your next turn.
When Wormfang Manta leaves the battlefield, you take an extra turn after this one.

Devouring Strossus

Flying, trample
At the beginning of your upkeep, sacrifice a creature.
Sacrifice a creature: Regenerate Devouring Strossus.

Colossal Whale

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever Colossal Whale attacks, you may exile target creature defending player controls until Colossal Whale leaves the battlefield. (That creature returns under its owner's control.)

Mage-Ring Responder

Mage-Ring Responder doesn't untap during your untap step.
{7}: Untap Mage-Ring Responder.
Whenever Mage-Ring Responder attacks, it deals 7 damage to target creature defending player controls.

Phyrexian Colossus

Phyrexian Colossus doesn't untap during your untap step.
Pay 8 life: Untap Phyrexian Colossus.
Phyrexian Colossus can't be blocked except by three or more creatures.

Lord of the Pit

Flying, trample
At the beginning of your upkeep, sacrifice a creature other than Lord of the Pit. If you can't, Lord of the Pit deals 7 damage to you.

Tolarian Serpent

At the beginning of your upkeep, mill seven cards.

Sanguine Praetor

{B}, Sacrifice a creature: Destroy each creature with the same mana value as the sacrificed creature.

Stone-Tongue Basilisk

Whenever Stone-Tongue Basilisk deals combat damage to a creature, destroy that creature at end of combat.
Threshold — As long as seven or more cards are in your graveyard, all creatures able to block Stone-Tongue Basilisk do so.

Leviathan

Trample
Leviathan enters tapped and doesn't untap during your untap step.
At the beginning of your upkeep, you may sacrifice two Islands. If you do, untap Leviathan.
Leviathan can't attack unless you sacrifice two Islands. (This cost is paid as attackers are declared.)

Colossus of Sardia

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Colossus of Sardia doesn't untap during your untap step.
{9}: Untap Colossus of Sardia. Activate only during your upkeep.

Tidal Force

At the beginning of each upkeep, you may tap or untap target permanent.

Stormtide Leviathan

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
All lands are Islands in addition to their other types.
Creatures without flying or islandwalk can't attack.

Polar Kraken

Trample
Polar Kraken enters tapped.
Cumulative upkeep—Sacrifice a land. (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.)

Jokulmorder

Trample
Jokulmorder enters tapped.
When Jokulmorder enters, sacrifice it unless you sacrifice five lands.
Jokulmorder doesn't untap during your untap step.
Whenever you play an Island, you may untap Jokulmorder.

Marjhan

Marjhan doesn't untap during your untap step.
{U}{U}, Sacrifice a creature: Untap Marjhan. Activate only during your upkeep.
Marjhan can't attack unless defending player controls an Island.
{U}{U}: Marjhan gets -1/-0 until end of turn and deals 1 damage to target attacking creature without flying.
When you control no Islands, sacrifice Marjhan.

Visions of Duplicity

Exchange control of two target creatures you don't control.
Flashback {8}{U}{U}. This spell costs {X} less to cast this way, where X is the greatest mana value of a commander you own on the battlefield or in the command zone. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Thing from the Deep

Whenever Thing from the Deep attacks, sacrifice it unless you sacrifice an Island.

Umbra Stalker

Chroma — Umbra Stalker's power and toughness are each equal to the number of black mana symbols in the mana costs of cards in your graveyard.

Fungal Shambler

Trample
Whenever Fungal Shambler deals damage to an opponent, you draw a card and that opponent discards a card.

Gargantuan Gorilla

At the beginning of your upkeep, you may sacrifice a Forest. If you sacrifice a snow Forest this way, Gargantuan Gorilla gains trample until end of turn. If you don't sacrifice a Forest, sacrifice Gargantuan Gorilla and it deals 7 damage to you.
{T}: Gargantuan Gorilla deals damage equal to its power to another target creature. That creature deals damage equal to its power to Gargantuan Gorilla.

Deep Spawn

Trample
At the beginning of your upkeep, sacrifice Deep Spawn unless you mill two cards.
{U}: Deep Spawn gains shroud until end of turn and doesn't untap during your next untap step. Tap Deep Spawn. (A creature with shroud can't be the target of spells or abilities.)

Infernal Denizen

At the beginning of your upkeep, sacrifice two Swamps. If you can't, tap Infernal Denizen, and an opponent may gain control of a creature you control of their choice for as long as Infernal Denizen remains on the battlefield.
{T}: Gain control of target creature for as long as Infernal Denizen remains on the battlefield.

Trench Behemoth

Return a land you control to its owner's hand: Untap Trench Behemoth. It gains hexproof until end of turn.
Landfall — Whenever a land you control enters, target creature an opponent controls attacks during its controller's next combat phase if able.