mtg.wtf

When Orcish Paratroopers enters the battlefield, flip it from a height of at least one foot. Sacrifice Orcish Paratroopers unless it turns over completely at least once during the flip and lands face up.

Flying, trample
When Orcus, Prince of Undeath enters the battlefield, choose one —
• Each other creature gets -X/-X until end of turn. You lose X life.
• Return up to X target creature cards with total mana value X or less from your graveyard to the battlefield. They gain haste until end of turn.

When Oreskos Explorer enters the battlefield, search your library for up to X Plains cards, where X is the number of players who control more lands than you. Reveal those cards, put them into your hand, then shuffle.

When Organ Hoarder enters the battlefield, look at the top three cards of your library, then put one of them into your hand and the rest into your graveyard.

When Ornery Kudu enters the battlefield, put a -1/-1 counter on target creature you control.

Flying
Tribute 2
When Ornitharch enters the battlefield, if tribute wasn't paid, create two 1/1 white Bird creature tokens with flying.

Orzhov Basilica enters the battlefield tapped.
When Orzhov Basilica enters the battlefield, return a land you control to its owner's hand.
{T}: Add {W}{B}.

Haunt
When Orzhov Euthanist enters the battlefield or the creature it haunts dies, destroy target creature that was dealt damage this turn.

Haunt
When Orzhov Pontiff enters the battlefield or the creature it haunts dies, choose one —
• Creatures you control get +1/+1 until end of turn.
• Creatures you don't control get -1/-1 until end of turn.

Enchant basic land you control
When Ossification enters the battlefield, exile target creature or planeswalker an opponent controls until Ossification leaves the battlefield.

When Ossuary Rats enters the battlefield, it deals X damage to target creature or planeswalker an opponent controls, where X is the number of creature cards in your graveyard.

When Oteclan Landmark enters the battlefield, scry 2.
Craft with artifact {2}{W}

When Oubliette enters the battlefield, target creature phases out until Oubliette leaves the battlefield. Tap that creature as it phases in this way.

When Out of Time enters the battlefield, untap all creatures, then those creatures phase out until Out of Time leaves the battlefield. Put a time counter on Out of Time for each creature that phased out this way.
Vanishing

When Outcaster Greenblade enters the battlefield, search your library for a basic land card or a Desert card, reveal it, put it into your hand, then shuffle.
Outcaster Greenblade gets +1/+1 for each Desert you control.

When Outcaster Trailblazer enters the battlefield, add one mana of any color.
Whenever another creature with power 4 or greater enters the battlefield under your control, draw a card.
Plot {2}{G}

When Outfitted Jouster enters the battlefield, conjure a card named Steelclaw Lance and a card named Brawler's Plate onto the battlefield and attach them to Outfitted Jouster.
If damage would be dealt to Outfitted Jouster while it's equipped, prevent that damage. When damage is prevented this way, sacrifice an Equipment attached to Outfitted Jouster.

When Outlaw Stitcher enters the battlefield, create a 2/2 blue and black Zombie Rogue creature token, then put two +1/+1 counters on that token for each spell you've cast this turn other than the first.
Plot {4}{U}

Chroma — When Outrage Shaman enters the battlefield, it deals damage to target creature equal to the number of red mana symbols in the mana costs of permanents you control.

Enchant opponent
When Overencumbered enters the battlefield, enchanted opponent creates a Clue token, a Food token, and a Junk token.
At the beginning of combat on enchanted opponent's turn, that player may pay {1} for each artifact they control. If they don't, creatures can't attack this combat.

When Overgrown Pest enters the battlefield, look at the top five cards of your library. You may reveal a land or double-faced card from among them and put that card into your hand. Put the rest on the bottom of your library in a random order.

When Overgrowth Elemental enters the battlefield, put a +1/+1 counter on another target Elemental you control.
Whenever another creature you control dies, you gain 1 life. If that creature was an Elemental, put a +1/+1 counter on Overgrowth Elemental.

Flying
When Overseer of the Damned enters the battlefield, you may destroy target creature.
Whenever a nontoken creature an opponent controls dies, create a tapped 2/2 black Zombie creature token.

When Overwhelmed Apprentice enters the battlefield, each opponent mills two cards. Then you scry 2.

When Overwhelmed Archivist enters the battlefield, draw a card, then discard a card.
Disturb {3}{U}