Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Ajani, Adversary of Tyrants

+1: Put a +1/+1 counter on each of up to two target creatures.
−2: Return target creature card with mana value 2 or less from your graveyard to the battlefield.
−7: You get an emblem with "At the beginning of your end step, create three 1/1 white Cat creature tokens with lifelink."

Arcane Signet

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

Three Visits

Search your library for a Forest card, put it onto the battlefield, then shuffle.

Island

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Simic Signet

Orzhov Signet

Selesnya Signet

Swamp

Atraxa, Praetors' Voice

Flying, vigilance, deathtouch, lifelink
At the beginning of your end step, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Carth the Lion

Whenever Carth the Lion enters or a planeswalker you control dies, look at the top seven cards of your library. You may reveal a planeswalker card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.
Planeswalkers' loyalty abilities you activate cost an additional [+1] to activate.

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Forest

Azorius Signet

Plains

Golgari Signet

Dimir Signet

Ajani, Inspiring Leader

+2: You gain 2 life. Put two +1/+1 counters on up to one target creature.
−3: Exile target creature. Its controller gains 2 life.
−10: Creatures you control gain flying and double strike until end of turn.