Plains

Impact Tremors

Whenever a creature you control enters, Impact Tremors deals 1 damage to each opponent.

Mountain

Inspiring Vantage

Inspiring Vantage enters tapped unless you control two or fewer other lands.
{T}: Add {R} or {W}.

Lifecreed Duo

Flying
Whenever another creature you control enters, you gain 1 life.

Divine Resilience

Kicker {2}{W} (You may pay an additional {2}{W} as you cast this spell.)
Target creature you control gains indestructible until end of turn. If this spell was kicked, instead any number of target creatures you control gain indestructible until end of turn. (Damage and effects that say "destroy" don't destroy them.)

Arabella, Abandoned Doll

Whenever Arabella, Abandoned Doll attacks, it deals X damage to each opponent and you gain X life, where X is the number of creatures you control with power 2 or less.

Hare Apparent

When this creature enters, create a number of 1/1 white Rabbit creature tokens equal to the number of other creatures you control named Hare Apparent.
A deck can have any number of cards named Hare Apparent.

Battlefield Forge

{T}: Add {C}.
{T}: Add {R} or {W}. Battlefield Forge deals 1 damage to you.

Another Round

Exile any number of creatures you control, then return them to the battlefield under their owner's control. Then repeat this process X more times.

Delney, Streetwise Lookout

Creatures you control with power 2 or less can't be blocked by creatures with power 3 or greater.
If an ability of a creature you control with power 2 or less triggers, that ability triggers an additional time.