Battered Golem

Battered Golem doesn't untap during your untap step.
Whenever an artifact enters, you may untap Battered Golem.

Lonis, Cryptozoologist

Whenever another nontoken creature you control enters, investigate.
{T}, Sacrifice X Clues: Target opponent reveals the top X cards of their library. You may put a nonland permanent card with mana value X or less from among them onto the battlefield under your control. That player puts the rest on the bottom of their library in a random order.

Coiling Oracle

When Coiling Oracle 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.

Llanowar Elves

Dream Stalker

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

Ulvenwald Mysteries

Whenever a nontoken creature you control dies, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Whenever you sacrifice a Clue, create a 1/1 white Human Soldier creature token.

Banishing Knack

Until end of turn, target creature gains "{T}: Return target nonland permanent to its owner's hand."

Wirewood Herald

When Wirewood Herald dies, you may search your library for an Elf card, reveal that card, put it into your hand, then shuffle.

Frilled Mystic

Flash
When Frilled Mystic enters, you may counter target spell.

Incubation Druid

{T}: Add one mana of any type that a land you control could produce. If Incubation Druid has a +1/+1 counter on it, add three mana of that type instead.
{3}{G}{G}: Adapt 3. (If this creature has no +1/+1 counters on it, put three +1/+1 counters on it.)

Crab Umbra

Enchant creature
{2}{U}: Untap enchanted creature.
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Man-o'-War

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

Erdwal Illuminator

Flying
Whenever you investigate for the first time each turn, investigate an additional time.

Whirler Rogue

When Whirler Rogue enters, create two 1/1 colorless Thopter artifact creature tokens with flying.
Tap two untapped artifacts you control: Target creature can't be blocked this turn.

Vigean Graftmage

Graft 2 (This creature enters with two +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
{1}{U}: Untap target creature with a +1/+1 counter on it.

Shrieking Drake

Flying
When Shrieking Drake enters, return a creature you control to its owner's hand.

Steelfin Whale

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Whenever an artifact you control enters, untap Steelfin Whale.

Ancestral Statue

When Ancestral Statue enters, return a nonland permanent you control to its owner's hand.

Retraction Helix

Immobilizing Ink

Enchant creature
Enchanted creature doesn't untap during its controller's untap step.
Enchanted creature has "{1}, Discard a card: Untap this creature."