Mounted Dreadknight

Trample
This creature enters with a +1/+1 counter on it if an opponent lost life this turn.

Pack's Betrayal

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. If you control a Wolf or Werewolf, scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Lunar Frenzy

Target creature you control gets +X/+0 and gains first strike and trample until end of turn.

Voldaren Stinger

This creature has first strike as long as it's attacking.
{2}{R}: This creature gets +2/+0 until end of turn.

Mountain

Harvesttide Assailant

Trample
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Harvesttide Infiltrator

Trample
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Harvesttide Infiltrator // Harvesttide Assailant

Falkenrath Perforator

Whenever this creature attacks, it deals 1 damage to defending player.

Stolen Vitality

Target creature gets +3/+1 until end of turn. If it's your turn, that creature gains trample until end of turn. Otherwise, it gains first strike until end of turn. (A creature with trample can deal excess combat damage to the player or planeswalker it's attacking. A creature with first strike deals combat damage before creatures without first strike.)

Famished Foragers

When this creature enters, if an opponent lost life this turn, add {R}{R}{R}.
{2}{R}, Discard a card: Draw a card.

Thermo-Alchemist

Defender
{T}: This creature deals 1 damage to each opponent.
Whenever you cast an instant or sorcery spell, untap this creature.

Thriving Bluff

This land enters tapped. As it enters, choose a color other than red.
{T}: Add {R} or one mana of the chosen color.

Falkenrath Pit Fighter

{1}{R}, Discard a card, Sacrifice a Vampire: Draw two cards. Activate only if an opponent lost life this turn.

Voldaren Ambusher

When this creature enters, if an opponent lost life this turn, it deals X damage to up to one target creature or planeswalker, where X is the number of Vampires you control.

Bloodthirsty Adversary

Haste
When this creature enters, you may pay {2}{R} any number of times. When you pay this cost one or more times, put that many +1/+1 counters on this creature, then exile up to that many target instant and/or sorcery cards with mana value 3 or less from your graveyard and copy them. You may cast any number of the copies without paying their mana costs.