Panharmonicon

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

Peregrine Drake

Flying
When this creature enters, untap up to five lands.

Coiling Oracle

When this creature enters, reveal the top card of your library. If it's a land card, put it onto the battlefield. Otherwise, put that card into your hand.

Gray Merchant of Asphodel

When this creature enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Mulldrifter

Flying
When this creature enters, draw two cards.
Evoke {2}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Plaguecrafter

When this creature enters, each player sacrifices a creature or planeswalker of their choice. Each player who can't discards a card.

Fleshbag Marauder

When this creature enters, each player sacrifices a creature of their choice.

Demon's Disciple

When this creature enters, each player sacrifices a creature or planeswalker of their choice.

Yarok, the Desecrated

Deathtouch, lifelink
If a permanent entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Aether Channeler

When this creature enters, choose one —
• Create a 1/1 white Bird creature token with flying.
• Return another target nonland permanent to its owner's hand.
• Draw a card.

Wood Elves

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

Cloud of Faeries

Flying
When this creature enters, untap up to two lands.
Cycling {2} ({2}, Discard this card: Draw a card.)

Farhaven Elf

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