Elesh Norn, Mother of Machines

Vigilance
If a permanent entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
Permanents entering don't cause abilities of permanents your opponents control to trigger.

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.

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.

Arcane Signet

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

Anointed Procession

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Roaming Throne

Ward {2}
As Roaming Throne enters, choose a creature type.
Roaming Throne is the chosen type in addition to its other types.
If a triggered ability of another creature you control of the chosen type triggers, it triggers an additional time.

Enduring Innocence

Lifelink
Whenever one or more other creatures you control with power 2 or less enter, draw a card. This ability triggers only once each turn.
When Enduring Innocence dies, if it was a creature, return it to the battlefield under its owner's control. It's an enchantment. (It's not a creature.)

Mondrak, Glory Dominus

If one or more tokens would be created under your control, twice that many of those tokens are created instead.
{1}{W/P}{W/P}, Sacrifice two other artifacts and/or creatures: Put an indestructible counter on Mondrak, Glory Dominus. ({W/P} can be paid with either {W} or 2 life.)

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Altar of the Brood

Whenever another permanent you control enters, each opponent mills a card.

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Sol Ring

Moonshaker Cavalry

Flying
When Moonshaker Cavalry enters, creatures you control gain flying and get +X/+X until end of turn, where X is the number of creatures you control.