Have

Cannibalize

Choose two target creatures controlled by the same player. Exile one of those creatures and put two +1/+1 counters on the other.

Fan Favorite

Assist (Another player can pay up to {3} of this spell's cost.)
{2}: This creature gets +1/+1 until end of turn. Any player may activate this ability.

Endbringer's Revel

{4}: Return target creature card from a graveyard to its owner's hand. Any player may activate this ability but only as a sorcery.

Dragon Blood

{3}, {T}: Put a +1/+1 counter on target creature.

Desynchronize

Target nonland permanent's owner puts it on their choice of the top or bottom of their library. Scry 2.

Volrath, the Shapestealer

At the beginning of combat on your turn, put a -1/-1 counter on up to one target creature.
{1}: Until your next turn, Volrath becomes a copy of target creature with a counter on it, except it's 7/5 and it has this ability.

Cleopatra, Exiled Pharaoh

Allies — At the beginning of your end step, put a +1/+1 counter on each of up to two other target legendary creatures.
Betrayal — Whenever a legendary creature with counters on it dies, draw a card for each counter on it. You lose 2 life.

Ertai's Scorn

This spell costs {U} less to cast if an opponent cast two or more spells this turn.
Counter target spell.

Starforged Sword

Gift a tapped Fish (You may promise an opponent a gift as you cast this spell. If you do, when it enters, they create a tapped 1/1 blue Fish creature token.)
When this Equipment enters, if the gift was promised, attach this Equipment to target creature you control.
Equipped creature gets +3/+3 and loses flying.
Equip {3}

Tetzimoc, Primal Death

Deathtouch
{B}, Reveal this card from your hand: Put a prey counter on target creature. Activate only during your turn.
When Tetzimoc enters, destroy each creature your opponents control with a prey counter on it.

Hidden Guerrillas

When an opponent casts an artifact spell, if this permanent is an enchantment, it becomes a 5/3 Soldier creature with trample.