Draconian Gate-Bot

When Draconian Gate-Bot enters the battlefield, choose one —
• Open an Attraction. (Put the top card of your Attraction deck onto the battlefield.)
• Destroy target Attraction. (It's put into its owner's junkyard.)

Kor Cartographer

When Kor Cartographer enters the battlefield, you may search your library for a Plains card, put it onto the battlefield tapped, then shuffle.

Soul Warden

Whenever another creature enters the battlefield, you gain 1 life.

Whitemane Lion

Flash
When Whitemane Lion enters the battlefield, return a creature you control to its owner's hand.

Changeling Hero

Changeling (This card is every creature type.)
Champion a creature (When this enters the battlefield, sacrifice it unless you exile another creature you control. When this leaves the battlefield, that card returns to the battlefield.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Skyscanner

Flying
When Skyscanner enters the battlefield, draw a card.

Stonehorn Dignitary

When Stonehorn Dignitary enters the battlefield, target opponent skips their next combat phase.

Kor Skyfisher

Flying
When Kor Skyfisher enters the battlefield, return a permanent you control to its owner's hand.

Soul's Attendant

Whenever another creature enters the battlefield, you may gain 1 life.

Guardians of Koilos

When Guardians of Koilos enters the battlefield, you may return another target historic permanent you control to its owner's hand. (Artifacts, legendaries, and Sagas are historic.)

Rambunctious Mutt

When Rambunctious Mutt enters the battlefield, destroy target artifact or enchantment an opponent controls.

Inspiring Overseer

Flying
When Inspiring Overseer enters the battlefield, you gain 1 life and draw a card.

Search Party Captain

This spell costs {1} less to cast for each creature you attacked with this turn.
When Search Party Captain enters the battlefield, draw a card.

Spirited Companion

When Spirited Companion enters the battlefield, draw a card.

Indoctrination Attendant

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When Indoctrination Attendant enters the battlefield, you may return another permanent you control to its owner's hand. If you do, create a 1/1 colorless Phyrexian Mite artifact creature token with toxic 1 and "This creature can't block."

Priest of Ancient Lore

When Priest of Ancient Lore enters the battlefield, you gain 1 life and draw a card.

Saltskitter

Whenever another creature enters the battlefield, exile Saltskitter. Return Saltskitter to the battlefield under its owner's control at the beginning of the next end step.