The Ozolith

Whenever a creature you control leaves the battlefield, if it had counters on it, put those counters on The Ozolith.
At the beginning of combat on your turn, if The Ozolith has counters on it, you may move all counters from The Ozolith onto target creature.

Eternal Witness

When this creature enters, you may return target card from your graveyard to your hand.

Sol Ring

Wood Elves

When this creature enters, search your library for a Forest card, put that card onto the battlefield, then shuffle.

Avenger of Zendikar

When this creature enters, create a 0/1 green Plant creature token for each land you control.
Landfall — Whenever a land you control enters, you may put a +1/+1 counter on each Plant creature you control.

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.

Reclamation Sage

When this creature enters, you may destroy target artifact or enchantment.

Farhaven Elf

When this creature enters, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Arcane Signet

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

Emiel the Blessed

{3}: Exile another target creature you control, then return it to the battlefield under its owner's control.
Whenever another creature you control enters, you may pay {G/W}. If you do, put a +1/+1 counter on it. If it's a Unicorn, put two +1/+1 counters on it instead. ({G/W} can be paid with either {G} or {W}.)

Thragtusk

When this creature enters, you gain 5 life.
When this creature leaves the battlefield, create a 3/3 green Beast creature token.