Mountain

Blood Curdle

Destroy target creature. Put a menace counter on a creature you control. (It can't be blocked except by two or more creatures.)

Angrath, Captain of Chaos

Creatures you control have menace.
−2: Amass Zombies 2. (Put two +1/+1 counters on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)

Nightsquad Commando

When Nightsquad Commando enters, if you attacked this turn, create a 1/1 white Human Soldier creature token.

Sonorous Howlbonder

Menace
Each creature you control with menace can't be blocked except by three or more creatures.

Bloodfell Caves

Bloodfell Caves enters tapped.
When Bloodfell Caves enters, you gain 1 life.
{T}: Add {B} or {R}.

Serrated Scorpion

When Serrated Scorpion dies, it deals 2 damage to each opponent and you gain 2 life.

Weaponize the Monsters

{2}, Sacrifice a creature: Weaponize the Monsters deals 2 damage to any target.

Obosh, the Preypiercer

Companion — Your starting deck contains only cards with odd mana values and land cards. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
If a source you control with an odd mana value would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Blazing Volley

Blazing Volley deals 1 damage to each creature your opponents control.

Grimdancer

Grimdancer enters with your choice of two different counters on it from among menace, deathtouch, and lifelink.

Frillscare Mentor

When Frillscare Mentor enters, put a menace counter on target non-Human creature you control. (It can't be blocked except by two or more creatures.)
{2}{R}, {T}: Put a +1/+1 counter on each creature you control with menace.

Whisper Squad

{1}{B}: Search your library for a card named Whisper Squad, put it onto the battlefield tapped, then shuffle.

Heightened Reflexes

Target creature gets +1/+0 until end of turn. Put a first strike counter on it.

Swamp

Labyrinth Raptor

Menace
Whenever a creature you control with menace becomes blocked, defending player sacrifices a creature blocking it.
{B}{R}: Creatures you control with menace get +1/+0 until end of turn.

Clash of Titans

Target creature fights another target creature. (Each deals damage equal to its power to the other.)