Papalymo Totolymo

Whenever you cast a noncreature spell, Papalymo Totolymo deals 1 damage to each opponent and you gain 1 life.
{4}, {T}, Sacrifice Papalymo Totolymo: Each opponent who lost life this turn sacrifices a creature with the greatest power among creatures they control.

Getting

Emet-Selch of the Third Seat

Spells you cast from your graveyard cost {2} less to cast.
Whenever one or more opponents lose life, you may cast target instant or sorcery card from your graveyard. If that spell would be put into your graveyard, exile it instead. Do this only once each turn.

Lyla, Holographic Assistant

Whenever you draw a card, put a +1/+1 counter on target creature.

Benthic Biomancer

{1}{U}: Adapt 1. (If this creature has no +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever one or more +1/+1 counters are put on this creature, draw a card, then discard a card.

Spider-Man 2099, Miguel O'Hara

When Spider-Man 2099 enters, return up to one target creature to its owner's hand.
Whenever one or more creatures you control deal combat damage to a player, draw a card.

Sire of Stagnation

Devoid (This card has no color.)
Whenever a land an opponent controls enters, that player exiles the top two cards of their library and you draw two cards.

Iron Spider, Stark Upgrade

Vigilance
{T}: Put a +1/+1 counter on each artifact creature and/or Vehicle you control.
{2}, Remove two +1/+1 counters from among artifacts you control: Draw a card.

Friendly Neighborhood

Enchant land
When this Aura enters, create three 1/1 green and white Human Citizen creature tokens.
Enchanted land has "{1}, {T}: Target creature gets +1/+1 until end of turn for each creature you control. Activate only as a sorcery."

Arasta of the Endless Web

Reach
Whenever an opponent casts an instant or sorcery spell, create a 1/2 green Spider creature token with reach.

Pumpkin Bombs

{T}, Discard two cards: Draw three cards, then put a fuse counter on this artifact. It deals damage equal to the number of fuse counters on it to target opponent. They gain control of this artifact.

Winternight Stories

Draw three cards. Then discard two cards unless you discard a creature card.
Harmonize {4}{U} (You may cast this card from your graveyard for its harmonize cost. You may tap a creature you control to reduce that cost by {X}, where X is its power. Then exile this spell.)

Impostor Syndrome

Whenever a nontoken creature you control deals combat damage to a player, create a token that's a copy of it, except it isn't legendary.