Divine Sacrament

White creatures get +1/+1.
Threshold — White creatures get an additional +1/+1 as long as seven or more cards are in your graveyard.

Branching Evolution

If one or more +1/+1 counters would be put on a creature you control, twice that many +1/+1 counters are put on that creature instead.

Kyler, Sigardian Emissary

Whenever another Human you control enters, put a +1/+1 counter on Kyler.
Other Humans you control get +1/+1 for each counter on Kyler.

Forced Adaptation

Enchant creature
At the beginning of your upkeep, put a +1/+1 counter on enchanted creature.

Laid to Rest

Whenever a Human you control dies, draw a card.
Whenever a creature you control with a +1/+1 counter on it dies, you gain 2 life.

Force of Virtue

If it's not your turn, you may exile a white card from your hand rather than pay this spell's mana cost.
Flash
Creatures you control get +1/+1.

Cathars' Crusade

Whenever a creature you control enters, put a +1/+1 counter on each creature you control.

Amazing Alliance

Creatures you control get +1/+1.
Whenever you attack with one or more legendary creatures, you gain that much life.

Court of Garenbrig

When this enchantment enters, you become the monarch.
At the beginning of your upkeep, distribute two +1/+1 counters among up to two target creatures. Then if you're the monarch, double the number of +1/+1 counters on each creature you control.

Ride the Shoopuf

Landfall — Whenever a land you control enters, put a +1/+1 counter on target creature you control.
{5}{G}{G}: This enchantment becomes a 7/7 Beast creature in addition to its other types.

Intangible Virtue

Creature tokens you control get +1/+1 and have vigilance.

Master Chef

Commander creatures you own have "This creature enters with an additional +1/+1 counter on it" and "Other creatures you control enter with an additional +1/+1 counter on them."

Hardened Scales

If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on it instead.

Anthem of Champions

Gaea's Anthem

Evolutionary Escalation

At the beginning of your upkeep, put three +1/+1 counters on target creature you control and three +1/+1 counters on target creature an opponent controls.

Mirari's Wake

Creatures you control get +1/+1.
Whenever you tap a land for mana, add one mana of any type that land produced.