Painful Quandary

Whenever an opponent casts a spell, that player loses 5 life unless they discard a card.

Sire of Stagnation

Devoid (This card has no color.)
Whenever a land an opponent controls enters, that player exiles the top two cards of their library and you draw two cards.

Yidris, Maelstrom Wielder

Trample
Whenever Yidris, Maelstrom Wielder deals combat damage to a player, as you cast spells from your hand this turn, they gain cascade. (When you cast the spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Nemesis of Reason

Whenever Nemesis of Reason attacks, defending player mills ten cards.

Defiler of Souls

Flying
At the beginning of each player's upkeep, that player sacrifices a monocolored creature of their choice.

Vile Consumption

All creatures have "At the beginning of your upkeep, sacrifice this creature unless you pay 1 life."

Tunnel Ignus

Whenever a land enters under an opponent's control, if that player had another land enter the battlefield under their control this turn, Tunnel Ignus deals 3 damage to that player.

Sarinth Greatwurm

Trample
Whenever a land enters, create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")

Polluted Bonds

Whenever a land an opponent controls enters, that player loses 2 life and you gain 2 life.

Tectonic Instability

Whenever a land enters, tap all lands its controller controls.

Dire Undercurrents

Whenever a blue creature you control enters, you may have target player draw a card.
Whenever a black creature you control enters, you may have target player discard a card.

Spectrum Sentinel

Protection from multicolored (This creature can't be blocked, targeted, dealt damage, enchanted, or equipped by anything multicolored.)
Whenever a nonbasic land an opponent controls enters, you gain 1 life.

Underworld Dreams

Whenever an opponent draws a card, Underworld Dreams deals 1 damage to that player.