Cathars' Crusade

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

Morophon, the Boundless

Changeling (This card is every creature type.)
As Morophon enters, choose a creature type.
Spells of the chosen type you cast cost {W}{U}{B}{R}{G} less to cast. This effect reduces only the amount of colored mana you pay.
Other creatures you control of the chosen type get +1/+1.

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.

Reflections of Littjara

As this enchantment enters, choose a creature type.
Whenever you cast a spell of the chosen type, copy that spell. (A copy of a permanent spell becomes a token.)

Aether Charge

Whenever a Beast you control enters, you may have it deal 4 damage to target opponent or planeswalker.

Quest for the Goblin Lord

Whenever a Goblin you control enters, you may put a quest counter on this enchantment.
As long as this enchantment has five or more quest counters on it, creatures you control get +2/+0.

Maskwood Nexus

Creatures you control are every creature type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.
{3}, {T}: Create a 2/2 blue Shapeshifter creature token with changeling. (It is every creature type.)

Dragon Tempest

Whenever a creature you control with flying enters, it gains haste until end of turn.
Whenever a Dragon you control enters, it deals X damage to any target, where X is the number of Dragons you control.

Resplendent Marshal

Flying
When this creature enters or dies, you may exile another creature card from your graveyard. When you do, put a +1/+1 counter on each creature you control other than this creature that shares a creature type with the exiled card.