Breathless Knight

Flying, lifelink
Whenever Breathless Knight or another creature you control enters, if that creature entered from a graveyard or you cast it from a graveyard, put a +1/+1 counter on Breathless Knight.

Adaptive Automaton

As this creature enters, choose a creature type.
This creature is the chosen type in addition to its other types.
Other creatures you control of the chosen type get +1/+1.

Species Specialist

As Species Specialist enters, choose a creature type.
Whenever a creature of the chosen type dies, you may draw a card.

Grey Host Reinforcements

Flying, ward {3}
When Grey Host Reinforcements enters, exile target player's graveyard. Put a number of +1/+1 counters on Grey Host Reinforcements equal to the number of creature cards exiled this way.

Hagra Constrictor

Hagra Constrictor enters with two +1/+1 counters on it.
Each creature you control with a +1/+1 counter on it has menace. (A creature with menace can't be blocked except by two or more creatures.)

Elite Scaleguard

When Elite Scaleguard enters, bolster 2. (Choose a creature with the least toughness among creatures you control and put two +1/+1 counters on it.)
Whenever a creature you control with a +1/+1 counter on it attacks, tap target creature defending player controls.

Metallic Mimic

As Metallic Mimic enters, choose a creature type.
Metallic Mimic is the chosen type in addition to its other types.
Each other creature you control of the chosen type enters with an additional +1/+1 counter on it.

Alesha, Who Smiles at Death

First strike
Whenever Alesha, Who Smiles at Death attacks, you may pay {W/B}{W/B}. If you do, return target creature card with power 2 or less from your graveyard to the battlefield tapped and attacking.

Bloodline Pretender

Changeling (This card is every creature type.)
As Bloodline Pretender enters, choose a creature type.
Whenever another creature you control of the chosen type enters, put a +1/+1 counter on Bloodline Pretender.

Nazgûl

Deathtouch
When Nazgûl enters, the Ring tempts you.
Whenever the Ring tempts you, put a +1/+1 counter on each Wraith you control.
A deck can have up to nine cards named Nazgûl.