Duskshell Crawler

When Duskshell Crawler enters, put a +1/+1 counter on target creature.
Each creature you control with a +1/+1 counter on it has trample.

Corpsejack Menace

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

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Slippery Bogbonder

Flash
Hexproof
When Slippery Bogbonder enters, put a hexproof counter on target creature. Then move any number of counters from among creatures you control onto that creature.

Wild Growth

Enchant land
Whenever enchanted land is tapped for mana, its controller adds an additional {G}.

Skullbriar, the Walking Grave

Haste
Whenever Skullbriar, the Walking Grave deals combat damage to a player, put a +1/+1 counter on it.
Counters remain on Skullbriar as it moves to any zone other than a player's hand or library.

Kaya's Ghostform

Enchant creature or planeswalker you control
When enchanted permanent dies or is put into exile, return that card to the battlefield under your control.

Kalonian Hydra

Trample
Kalonian Hydra enters with four +1/+1 counters on it.
Whenever Kalonian Hydra attacks, double the number of +1/+1 counters on each creature you control.

Grafted Growth

Enchant land
When Grafted Growth enters, put a +1/+1 counter on target creature or Vehicle you control.
Enchanted land has "{T}: Add two mana of any one color."

Hydra's Growth

Enchant creature
When Hydra's Growth enters, put a +1/+1 counter on enchanted creature.
At the beginning of your upkeep, double the number of +1/+1 counters on enchanted creature.

Grimdancer

Grimdancer enters with your choice of two different counters on it from among menace, deathtouch, and lifelink.