Whenever Omnoid Destroyer or another artifact you control enters, artifact creatures you control gain deathtouch until end of turn.

Whenever you spend at least five mana to cast a spell, untap Opal-Eye Runeweaver.
{T}: Untap another target permanent not named Opal-Eye Runeweaver. Activate only as a sorcery.

Open Air Boardwalk enters tapped.
{T}: Add {G} or {W}.
{4}: Make a pledge. Activate only as a sorcery.

Outlands Prowler has first strike as long as it's your turn.
Landfall — Whenever a land you control enters, Outlands Prowler gets +2/+2 until end of turn.

At the beginning of your first main phase, you may add one mana of any type.

Ozzen Headquarters enters tapped.
{T}: Add {W} or {B}.
{T}, Discard another card named Ozzen Headquarters: Draw a card.

When Padpole enters, create a Berry token.
Surface {3}{G}

When Pathetic Cocoon enters or dies, create a Berry token.

Menace
At the beginning of your end step, if you've sacrificed a permanent this turn, you may discard a card. If you do, draw a card.

At the beginning of combat on your turn, if you've spent at least five mana to cast spells this turn, Peaktop Predator deals 2 damage to target player or planeswalker.

When Penrath Ambassador enters, target creature must be blocked each combat this turn if able and target creature can't block this turn.
Basic landcycling {1}{G}

Flying
Whenever you attack, target attacking creature gets +1/+1 until end of turn. If you control a green permanent, instead put a +1/+1 counter on that creature.

When Pensive Caldera enters, 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, target creature you don't control doesn't untap during its controller's next untap step.

{T}: Add one mana of any color.
{1}{VP}{VP}{VP}, {T}, Sacrifice Petabyte Prism: Draw two cards.

Vigilance
Whenever Pheres-Band Huntmaster becomes the target of a spell or ability you control, put a +1/+1 counter on it. You gain 2 life.

First strike
When Photon Collector enters, scry 2.

When Photonic Cobra dies, create a 1/1 red and green Elemental creature token.

Deathtouch
Whenever Pidae Raider deals combat damage to a player, create a Treasure token.

This spell costs {1} less to cast for each counter among permanents you control.
Ward {2}

Amity — When you cast this spell, copy it if you attacked with exactly two creatures this turn. You may choose new targets for the copy.
Target creature gets +0/+2 and gains hexproof until end of turn.

When Plasma Armory enters or leaves the battlefield, create a Weapon token.
{2}, Sacrifice Plasma Armory: Draw a card.

Each player mills two cards. When you do, return target creature card from your graveyard to your hand.

Landfall — Whenever a land you control enters, Plucky Trainer gets +2/+2 until end of turn.