Flash
When Omen of Deception enters the battlefield, counter target spell unless its controller pays {2}.
{2}{U}, Sacrifice Omen of Deception: Scry 2.

Flash
When Omen of Horizons enters the battlefield, put two +1/+1 counters on target creature you control.
{2}{G}, Sacrifice Omen of Horizons: Scry 2.

Flash
When Omen of Slaughter enters the battlefield, each opponent sacrifices a creature or planeswalker.
{2}{B}, Sacrifice Omen of Slaughter: Scry 2.

Flash
When Omen of Storms enters the battlefield, discard a card, then draw two cards.
{2}{R}, Sacrifice Omen of Storms: Scry 2.

Flash
When Omen of Victory enters the battlefield, create a 0/0 white Army creature token, then put two +1/+1 counter on it.
{2}{W}, Sacrifice Omen of Victory: Scry 2.

Enchant creature
When Ordained Penitence enters the battlefield, you may put a lifelink counter on target creature you control.
Enchanted creature can't attack or block, and its activated abilities can't be activated.

When Paladin of the Crownguard enters the battlefield, you gain 3 life.
Paladin of the Crownguard has first strike as long as it's your turn.

When Patron of Ephara's Glory enters the battlefield, create a 0/1 colorless Sculpture artifact creature token.
Whenever a creature you control dies, scry 1, then you gain 1 life.

When Pensive Caldera enters the battlefield, you may discard a card. If you do, draw a card.
{T}: Add {R}. Spend this mana only to cast artifact, instant, or sorcery spells.

Flash
When Permafrost Lynx enters the battlefield, target creature you don't control doesn't untap during its controller's next untap step.

Flash
When Permafrost Tiger enters the battlefield, you may have it fight target creature that entered the battlefield this turn.

When Phenax's Touch enters the battlefield, each opponent discards a card and loses 1 life.
{1}{B}, Sacrifice Phenax's Touch: You draw a card and you lose 1 life.

First strike
When Photon Collector enters the battlefield, scry 2.

When Phyto's Offshoot enters the battlefield, you may exile any number of permanent cards from your graveyard. When you do, target opponent reveals that many cards from their hand. You choose one of them. That player discards that card.
When Phyto's Offshoot leaves your graveyard, exile all cards from your opponents' graveyards.

When Player Band enters the battlefield, create a 2/3 colorless Bard creature token, then attach Player Band to it.
Equipped creature gets +1/+1.
{1}, Unattach Player Band: Tap equipped creature. It gains hexproof until end of turn.
Equip {3}

Flying
When Powerline Warbler enters the battlefield, return target artifact card from your graveyard to your hand.

When Primal Pathbreaker enters the battlefield, search your library for a basic land card, put it onto the battlefield, then shuffle. Then if you control eight or more lands, that land becomes a 4/4 green Elemental creature. It's still a land.

Flash
When Primordial of Emila Glade enters the battlefield, return up to two instant and/or sorcery cards from your graveyard to your hand.
Once each turn, you may pay {U} rather than pay the mana cost for an instant or sorcery spell.

When Prismatic Remnant enters the battlefield, scry 2.

As an additional cost to cast spells during an opponent's turn, you may pay {U} and reveal Promethean Jaxl from your hand. If you do, you get a lurk counter.
Flash
Promethean Jaxl enters the battlefield tapped.
When Promethean Jaxl enters the battlefield, you draw a card for each lurk counter you have, then you lose all lurk counters.

Flying
When Prototypical Broodwing enters the battlefield, choose one —
• Return target creature to its owner's hand.
• Return target instant or sorcery card from your graveyard to your hand.

Flash
Ward {4}
When Psychedelic Serpent enters the battlefield, gain control of target instant spell, sorcery spell, activated ability, or triggered ability. You may choose new targets for it.

Revolt — When Pureheart Cavalier enters the battlefield, if a permanent you controlled left the battlefield this turn, create a 1/1 red Soldier creature token.

When Rallying the Revolutionaries enters the battlefield, draw a card.
Activated abilities of creatures you control cost up to {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.

When Rano's Slopeguard enters the battlefield, you may exile cards from the top of your library until you exile a nonland card with mana value 2 or less, then put the rest on the bottom in a random order. You may cast the exiled card this turn.