Skullclamp

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

Tome of Legends

Tome of Legends enters with a page counter on it.
Whenever your commander enters or attacks, put a page counter on Tome of Legends.
{1}, {T}, Remove a page counter from Tome of Legends: Draw a card.

Ivy Lane Denizen

Whenever another green creature you control enters, put a +1/+1 counter on target creature.

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Loran, Disciple of History

Whenever Loran, Disciple of History or another legendary creature you control enters, return target artifact card from your graveyard to your hand.

Purphoros, God of the Forge

Indestructible
As long as your devotion to red is less than five, Purphoros isn't a creature.
Whenever another creature you control enters, Purphoros deals 2 damage to each opponent.
{2}{R}: Creatures you control get +1/+0 until end of turn.

Soul of the Harvest

Trample
Whenever another nontoken creature you control enters, you may draw a card.

Outpost Siege

As Outpost Siege enters, choose Khans or Dragons.
• Khans — At the beginning of your upkeep, exile the top card of your library. Until end of turn, you may play that card.
• Dragons — Whenever a creature you control leaves the battlefield, Outpost Siege deals 1 damage to any target.

Radiant Solar

Flying, lifelink
Whenever Radiant Solar or another nontoken creature you control enters, venture into the dungeon. (Enter the first room or advance to the next room.)
{W}, Discard Radiant Solar: Venture into the dungeon and you gain 3 life.

Reinforced Ronin

Haste
At the beginning of your end step, return Reinforced Ronin to its owner's hand.
Channel — {1}{R}, Discard Reinforced Ronin: Draw a card.

Norin the Wary

When a player casts a spell or a creature attacks, exile Norin the Wary. Return it to the battlefield under its owner's control at the beginning of the next end step.

Champion of Lambholt

Creatures with power less than Champion of Lambholt's power can't block creatures you control.
Whenever another creature you control enters, put a +1/+1 counter on Champion of Lambholt.

Samwise Gamgee

Whenever another nontoken creature you control enters, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
Sacrifice three Foods: Return target historic card from your graveyard to your hand. (Artifacts, legendaries, and Sagas are historic.)

Gylwain, Casting Director

Whenever Gylwain, Casting Director or another nontoken creature you control enters, choose one —
• Create a Royal Role token attached to that creature.
• Create a Sorcerer Role token attached to that creature.
• Create a Monster Role token attached to that creature.

Gimli of the Glittering Caves

Double strike
Whenever another legendary creature you control enters, put a +1/+1 counter on Gimli of the Glittering Caves.
Whenever Gimli deals combat damage to a player, create a Treasure token.

Chain Reaction

Chain Reaction deals X damage to each creature, where X is the number of creatures on the battlefield.

Rocco, Cabaretti Caterer

When Rocco, Cabaretti Caterer enters, if you cast it, you may search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Rumor Gatherer

Alliance — Whenever another creature you control enters, scry 1. If this is the second time this ability has resolved this turn, draw a card instead.

Warstorm Surge

Whenever a creature you control enters, it deals damage equal to its power to any target.

Spirit Bonds

Whenever a nontoken creature you control enters, you may pay {W}. If you do, create a 1/1 white Spirit creature token with flying.
{1}{W}, Sacrifice a Spirit: Target non-Spirit creature gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Rose Room Treasurer

Alliance — Whenever another creature you control enters, create a Treasure token if this is the first or second time this ability has resolved this turn. Otherwise, you may pay {X}. When you do, Rose Room Treasurer deals X damage to any target.

Panharmonicon

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

Thorn Mammoth

Trample
Whenever Thorn Mammoth or another creature you control enters, Thorn Mammoth fights up to one target creature you don't control.

Confusion in the Ranks

Whenever an artifact, creature, or enchantment enters, its controller chooses target permanent another player controls that shares a card type with it. Exchange control of those permanents.

Solemn Simulacrum

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

Genesis Chamber

Whenever a nontoken creature enters, if Genesis Chamber is untapped, that creature's controller creates a 1/1 colorless Myr artifact creature token.

Mentor of the Meek

Whenever another creature you control with power 2 or less enters, you may pay {1}. If you do, draw a card.

Lossarnach Captain

First strike
Whenever Lossarnach Captain or another Human you control enters, tap target creature an opponent controls.
At the beginning of your upkeep, create a 1/1 white Human Soldier creature token.

Aura Shards

Whenever a creature you control enters, you may destroy target artifact or enchantment.

Witty Roastmaster

Alliance — Whenever another creature you control enters, Witty Roastmaster deals 1 damage to each opponent.

Legolas Greenleaf

Reach
Legolas Greenleaf can't be blocked by creatures with power 2 or less.
Whenever another legendary creature you control enters, put a +1/+1 counter on Legolas Greenleaf.
Whenever Legolas Greenleaf deals combat damage to a player, draw a card.

Théoden, King of Rohan

Whenever Théoden, King of Rohan or another Human you control enters, target creature gains double strike until end of turn.

Gala Greeters

Alliance — Whenever another creature you control enters, choose one that hasn't been chosen this turn —
• Put a +1/+1 counter on Gala Greeters.
• Create a tapped Treasure token.
• You gain 2 life.