Dark Ritual

Ruthless Technomancer

When this creature enters, you may sacrifice another creature you control. If you do, create a number of Treasure tokens equal to that creature's power.
{2}{B}, Sacrifice X artifacts: Return target creature card with power X or less from your graveyard to the battlefield. X can't be 0.

Sol Ring

Bebop & Rocksteady

Whenever Bebop & Rocksteady attack or block, sacrifice a permanent unless you discard a card.

Elves of Deep Shadow

{T}: Add {B}. This creature deals 1 damage to you.

Llanowar Elves

The Gitrog, Ravenous Ride

Trample, haste
Whenever The Gitrog deals combat damage to a player, you may sacrifice a creature that saddled it this turn. If you do, draw X cards, then put up to X land cards from your hand onto the battlefield tapped, where X is the sacrificed creature's power.
Saddle 1

Yargle and Multani

Selvala, Heart of the Wilds

Whenever another creature enters, its controller may draw a card if its power is greater than each other creature's power.
{G}, {T}: Add X mana in any combination of colors, where X is the greatest power among creatures you control.

Elvish Mystic

Baloth Prime

This creature enters tapped with six stun counters on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)
Whenever you sacrifice a land, create a tapped 4/4 green Beast creature token and untap this creature.
{4}, Sacrifice a land: You gain 2 life.