Arcane Signet

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

Explore

You may play an additional land this turn.
Draw a card.

Mountain

Rootbound Crag

Rootbound Crag enters tapped unless you control a Mountain or a Forest.
{T}: Add {R} or {G}.

Borborygmos Enraged

Trample
Whenever Borborygmos Enraged deals combat damage to a player, reveal the top three cards of your library. Put all land cards revealed this way into your hand and the rest into your graveyard.
Discard a land card: Borborygmos Enraged deals 3 damage to any target.

Sol Ring

Forest

Defense Grid

Each spell costs {3} more to cast except during its controller's turn.

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Azusa, Lost but Seeking

You may play two additional lands on each of your turns.

Explorer's Cache

Explorer's Cache enters with two +1/+1 counters on it.
Whenever a creature you control with a +1/+1 counter on it dies, put a +1/+1 counter on Explorer's Cache.
{T}: Move a +1/+1 counter from Explorer's Cache onto target creature. Activate only as a sorcery.