Bone Splinters

As an additional cost to cast this spell, sacrifice a creature.
Destroy target creature.

Phyrexian Vivisector

Whenever a creature you control dies, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Sengir Connoisseur

Flying
Whenever one or more other creatures die, put a +1/+1 counter on Sengir Connoisseur. This ability triggers only once each turn.

Cult Conscript

Cult Conscript enters tapped.
{1}{B}: Return Cult Conscript from your graveyard to the battlefield. Activate only if a non-Skeleton creature died under your control this turn.

Braids, Arisen Nightmare

At the beginning of your end step, you may sacrifice an artifact, creature, enchantment, land, or planeswalker. If you do, each opponent may sacrifice a permanent that shares a card type with it. For each opponent who doesn't, that player loses 2 life and you draw a card.

Tyrannical Pitlord

Flying, trample
As Tyrannical Pitlord enters, choose another creature you control.
The chosen creature gets +3/+3 and has flying.
When Tyrannical Pitlord leaves the battlefield, sacrifice the chosen creature.

Swamp

Braids's Frightful Return

Read ahead (Choose a chapter and start with that many lore counters. Add one after your draw step. Skipped chapters don't trigger. Sacrifice after III.)
I — You may sacrifice a creature. If you do, each opponent discards a card.
II — Return target creature card from your graveyard to your hand.
III — Target opponent may sacrifice a nonland, nontoken permanent. If they don't, they lose 2 life and you draw a card.

Phyrexian Rager

When Phyrexian Rager enters, you draw a card and you lose 1 life.

Gibbering Barricade

Defender
{2}{B}, Sacrifice a creature: You gain 1 life and draw a card.

Battle-Rage Blessing

Target creature gains deathtouch and indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Cut Down

Destroy target creature with total power and toughness 5 or less.

Splatter Goblin

When Splatter Goblin dies, target creature an opponent controls gets -1/-1 until end of turn.