Dream Stalker

When Dream Stalker enters, return a permanent you control to its owner's hand.

Gryff Vanguard

Flying
When Gryff Vanguard enters, draw a card.

Muse Drake

Flying
When Muse Drake enters, draw a card.

Tome Raider

Flying
When Tome Raider enters, draw a card.

Run Away Together

Choose two target creatures controlled by different players. Return those creatures to their owners' hands.

Man-o'-War

When Man-o'-War enters, return target creature to its owner's hand.

Sage's Row Denizen

Whenever another blue creature you control enters, target player mills two cards.

Wall of Runes

Defender (This creature can't attack.)
When Wall of Runes enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Vedalken Dismisser

When Vedalken Dismisser enters, put target creature on top of its owner's library.

Venture Deeper

Target player mills four cards. (Then exile this card. You may cast the creature later from exile.)

Merfolk Secretkeeper

Merfolk Secretkeeper // Venture Deeper

Combat Courier

{2}, Sacrifice Combat Courier: Draw a card.
Unearth {U} ({U}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Cloudkin Seer

Flying
When Cloudkin Seer enters, draw a card.

Drag Under

Return target creature to its owner's hand.
Draw a card.

Sea Gate Oracle

When Sea Gate Oracle enters, look at the top two cards of your library. Put one of them into your hand and the other on the bottom of your library.

Vedalken Entrancer

Roaming Ghostlight

Flying
When Roaming Ghostlight enters, return up to one target non-Spirit creature to its owner's hand.

Riptide Turtle

Thassa's Devourer

Constellation — Whenever Thassa's Devourer or another enchantment you control enters, target player mills two cards.

Island

Doorkeeper

Defender
{2}{U}, {T}: Target player mills X cards, where X is the number of creatures you control with defender.