ETB Triggers

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Essence Warden

Whenever another creature enters, you gain 1 life.

Give Fodder

Rasputin, the Oneiromancer

When Rasputin, the Oneiromancer enters, put a dream counter on it for each opponent you have. Each opponent creates a 1/1 red Goblin creature token.
{T}, Remove one or more dream counters from Rasputin: Add that much {C}.
{T}, Remove a dream counter from Rasputin: Create a 2/2 white Knight creature token with protection from red.

ETB Payoff

Amalia Benavides Aguirre

Ward—Pay 3 life.
Whenever you gain life, Amalia Benavides Aguirre explores. Then destroy all other creatures if its power is exactly 20. (To have this creature explore, reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard.)

Starscape Cleric

Offspring {2}{B} (You may pay an additional {2}{B} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Flying
This creature can't block.
Whenever you gain life, each opponent loses 1 life.

Xyris, the Writhing Storm

Flying
Whenever an opponent draws a card except the first one they draw in each of their draw steps, create a 1/1 green Snake creature token.
Whenever Xyris, the Writhing Storm deals combat damage to a player, you and that player each draw that many cards.

Sanguine Bond

Whenever you gain life, target opponent loses that much life.

Dina, Soul Steeper

Whenever you gain life, each opponent loses 1 life.
{1}, Sacrifice another creature: Dina, Soul Steeper gets +X/+0 until end of turn, where X is the sacrificed creature's power.

Rampaging Ferocidon

Menace
Players can't gain life.
Whenever another creature enters, Rampaging Ferocidon deals 1 damage to that creature's controller.

Soul Warden

The War Games

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after IV.)
I — Each player creates three tapped 1/1 white Warrior creature tokens. The tokens are goaded for as long as The War Games remains on the battlefield.
II, III — Put a +1/+1 counter on each Warrior creature.
IV — You may exile a nontoken creature you control. When you do, exile all Warriors.

Blink

Changeling Berserker

Changeling (This card is every creature type.)
Haste
Champion a creature (When this enters, sacrifice it unless you exile another creature you control. When this leaves the battlefield, that card returns to the battlefield.)

Hunted Phantasm

Hunted Phantasm can't be blocked.
When Hunted Phantasm enters, target opponent creates five 1/1 red Goblin creature tokens.

Hansk, Slayer Zealot

At the beginning of your upkeep, target opponent creates three Walker tokens. (They're 2/2 black Zombie creatures.)
{T}: Hansk, Slayer Zealot deals 2 damage to target creature.
Whenever a Zombie an opponent controls dies, draw a card.

Suture Priest

Whenever another creature you control enters, you may gain 1 life.
Whenever a creature an opponent controls enters, you may have that player lose 1 life.

Trespasser's Curse

Enchant player
Whenever a creature enchanted player controls enters, that player loses 1 life and you gain 1 life.

Eiganjo Uprising

Create X 2/2 white Samurai creature tokens with vigilance. They gain menace and haste until end of turn.
Each opponent creates X minus one 2/2 white Samurai creature tokens with vigilance.

Blood Seeker

Whenever a creature an opponent controls enters, you may have that player lose 1 life.

Dual Nature

Whenever a nontoken creature enters, its controller creates a token that's a copy of that creature.
Whenever a nontoken creature leaves the battlefield, exile all tokens with the same name as that creature.
When Dual Nature leaves the battlefield, exile all tokens created with Dual Nature.

Poisonbelly Ogre

Whenever another creature enters, its controller loses 1 life.

Drogskol Reaver

Flying, double strike, lifelink
Whenever you gain life, draw a card.

Trelasarra, Moon Dancer

Whenever you gain life, put a +1/+1 counter on Trelasarra, Moon Dancer and scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Authority of the Consuls

Creatures your opponents control enter tapped.
Whenever a creature an opponent controls enters, you gain 1 life.

Epicure of Blood

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.

Vito, Thorn of the Dusk Rose

Whenever you gain life, target opponent loses that much life.
{3}{B}{B}: Creatures you control gain lifelink until end of turn.

Defiant Bloodlord

Flying
Whenever you gain life, target opponent loses that much life.

Auriok Champion

Protection from black and from red
Whenever another creature enters, you may gain 1 life.

Enduring Tenacity

Whenever you gain life, target opponent loses that much life.
When Enduring Tenacity dies, if it was a creature, return it to the battlefield under its owner's control. It's an enchantment. (It's not a creature.)