Myr Scrapling

Sacrifice Myr Scrapling: Put a +1/+1 counter on target creature.

Sparring Construct

When Sparring Construct dies, put a +1/+1 counter on target creature you control.

Tree of Tales

Village Rites

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Hunger of the Howlpack

Put a +1/+1 counter on target creature.
Morbid — Put three +1/+1 counters on that creature instead if a creature died this turn.

Servant of the Scale

Servant of the Scale enters with a +1/+1 counter on it.
When Servant of the Scale dies, put X +1/+1 counters on target creature you control, where X is the number of +1/+1 counters on Servant of the Scale.

Iron Apprentice

Iron Apprentice enters with a +1/+1 counter on it.
When Iron Apprentice dies, if it had counters on it, put those counters on target creature you control.

Mortician Beetle

Whenever a player sacrifices a creature, you may put a +1/+1 counter on Mortician Beetle.

Gixian Infiltrator

Whenever you sacrifice another permanent, put a +1/+1 counter on Gixian Infiltrator.

Snow-Covered Forest

Vault of Whispers

Forest

Mold Folk

Lifelink
Mold Harvest — {1}, Sacrifice another creature or an artifact: Put a +1/+1 counter on Mold Folk.

Swamp

Carrion Feeder

Carrion Feeder can't block.
Sacrifice a creature: Put a +1/+1 counter on Carrion Feeder.

Smell Fear

Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Target creature you control fights up to one target creature you don't control.