Vampire Aristocrat

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

Unifying Theory

Whenever a player casts a spell, that player may pay {2}. If the player does, they draw a card.

Infantry Veteran

{T}: Target attacking creature gets +1/+1 until end of turn.

Ob Nixilis of the Black Oath

+2: Each opponent loses 1 life. You gain life equal to the life lost this way.
−2: Create a 5/5 black Demon creature token with flying. You lose 2 life.
−8: You get an emblem with "{1}{B}, Sacrifice a creature: You gain X life and draw X cards, where X is the sacrificed creature's power."
Ob Nixilis of the Black Oath can be your commander.

Black Lotus

{T}, Sacrifice Black Lotus: Add three mana of any one color.

Loathsome Troll

{3}{G}: Roll a d20. Activate only if Loathsome Troll is in your graveyard.
1—9 | Put Loathsome Troll on top of your library.
10—19 | Return Loathsome Troll to your hand.
20 | Return Loathsome Troll to the battlefield tapped.

Young Pyromancer

Whenever you cast an instant or sorcery spell, create a 1/1 red Elemental creature token.

Samite Alchemist

{W}{W}, {T}: Prevent the next 4 damage that would be dealt this turn to target creature you control. Tap that creature. It doesn't untap during your next untap step.

Emergent Growth

Target creature gets +5/+5 until end of turn and must be blocked this turn if able.

Oath of Ajani

When Oath of Ajani enters, put a +1/+1 counter on each creature you control.
Planeswalker spells you cast cost {1} less to cast.