Cryptic Trilobite

Cryptic Trilobite enters the battlefield with X +1/+1 counters on it.
Remove a +1/+1 counter from Cryptic Trilobite: Add {C}{C}. Spend this mana only to activate abilities.
{1}, {T}: Put a +1/+1 counter on Cryptic Trilobite.

Titania, Protector of Argoth

When Titania, Protector of Argoth enters the battlefield, return target land card from your graveyard to the battlefield.
Whenever a land you control is put into a graveyard from the battlefield, create a 5/3 green Elemental creature token.

Good-Fortune Unicorn

Whenever another creature enters the battlefield under your control, put a +1/+1 counter on that creature.

Pitiless Plunderer

Whenever another creature you control dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")