Demonic Rising

At the beginning of your end step, if you control exactly one creature, create a 5/5 black Demon creature token with flying.

Act of Treason

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. (It can attack and {T} this turn.)

Mountain

Harness by Force

Strive — This spell costs {2}{R} more to cast for each target beyond the first.
Gain control of any number of target creatures until end of turn. Untap those creatures. They gain haste until end of turn.

Dragonskull Summit

This land enters tapped unless you control a Swamp or a Mountain.
{T}: Add {B} or {R}.

Hijack

Gain control of target artifact or creature until end of turn. Untap it. It gains haste until end of turn.

Traitorous Blood

Gain control of target creature until end of turn. Untap it. It gains trample and haste until end of turn.

Kari Zev's Expertise

Gain control of target creature or Vehicle until end of turn. Untap it. It gains haste until end of turn.
You may cast a spell with mana value 2 or less from your hand without paying its mana cost.

Swamp

Disciple of Bolas

When this creature enters, sacrifice another creature. You gain X life and draw X cards, where X is that creature's power.

Sarkhan the Mad

0: Reveal the top card of your library and put it into your hand. Sarkhan deals damage to himself equal to that card's mana value.
−2: Target creature's controller sacrifices it, then that player creates a 5/5 red Dragon creature token with flying.
−4: Each Dragon creature you control deals damage equal to its power to target player or planeswalker.

Yahenni, Undying Partisan

Haste
Whenever a creature an opponent controls dies, put a +1/+1 counter on Yahenni.
Sacrifice another creature: Yahenni gains indestructible until end of turn.

Mark of Mutiny

Gain control of target creature until end of turn. Put a +1/+1 counter on it and untap it. That creature gains haste until end of turn. (It can attack and {T} this turn.)

Bloodthrone Vampire

Sacrifice a creature: This creature gets +2/+2 until end of turn.

Mizzium Mortars

Mizzium Mortars deals 4 damage to target creature you don't control.
Overload {3}{R}{R}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Shackles of Treachery

Gain control of target creature until end of turn. Untap that creature. Until end of turn, it gains haste and "Whenever this creature deals damage, destroy target Equipment attached to it."

Disciple of Griselbrand

{1}, Sacrifice a creature: You gain life equal to the sacrificed creature's toughness.

Falkenrath Aristocrat

Flying, haste
Sacrifice a creature: This creature gains indestructible until end of turn. If the sacrificed creature was a Human, put a +1/+1 counter on this creature.

Zealous Conscripts

Haste
When this creature enters, gain control of target permanent until end of turn. Untap that permanent. It gains haste until end of turn.