The Hobbit

Enchantment

Whenever a Mountain you control enters, put a quest counter on this enchantment. If it has six or more quest counters on it, sacrifice it. If you do, search your hand and/or library for a Dragon card and put it onto the battlefield. If you search your library this way, shuffle.
Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Last Light of Durin's Day

The Hobbit Eternal

Creature — Elephant

Trample
Whenever this creature attacks, another target creature you control gets +2/+0 and gains trample until end of turn.
Mountaincycling {1} ({1}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Oliphaunt

Teenage Mutant Ninja Turtles

Legendary Creature — Dinosaur Soldier

Reach, trample
When Zog enters, target creature can't block this turn.
Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Zog, Triceraton Castaway

Avatar: The Last Airbender

Creature — Mongoose Lizard

Menace (This creature can't be blocked except by two or more creatures.)
When this creature enters, it deals 1 damage to any target.
Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Mongoose Lizard

Final Fantasy

Creature — Giant

Trample, haste
Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Hill Gigas

Final Fantasy Commander

Artifact Creature — Construct

Menace
When this creature dies, each player may discard their hand and draw seven cards.
Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Ruin Grinder

Duskmourn: House of Horror

Creature — Beast

Menace (This creature can't be blocked except by two or more creatures.)
Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Bedhead Beastie

The Lost Caverns of Ixalan

Creature — Dinosaur

Trample
{2}{R}, Sacrifice a land: Draw a card.
Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Seismic Monstrosaur

March of the Machine

Creature — Phyrexian Giant

Haste
Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Furnace Host Charger

Creature — Yeti

Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)
Backup 2 (When this creature enters, put two +1/+1 counters on target creature. If that's another creature, it gains the following ability until end of turn.)
Trample

Cragsmasher Yeti

The List

Creature — Cat Beast

{R}: This creature gets +1/+0 until end of turn.
Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Chartooth Cougar

Commander 2013

Mountaincycling {2}, forestcycling {2} ({2}, Discard this card: Search your library for a Mountain or Forest card, reveal it, put it into your hand, then shuffle.)

Valley Rannet

Duel Decks: Ajani vs. Nicol Bolas

Creature — Elemental

Haste
Swampcycling {2}, mountaincycling {2} ({2}, Discard this card: Search your library for a Swamp or Mountain card, reveal it, put it into your hand, then shuffle.)