Enlightened Tutor

Search your library for an artifact or enchantment card, reveal it, then shuffle and put that card on top.

Kormus Bell

All Swamps are 1/1 black creatures that are still lands.

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

Guardian Zendikon

Enchant land
Enchanted land is a 2/6 white Wall creature with defender. It's still a land.
When enchanted land dies, return that card to its owner's hand.

Elesh Norn, Grand Cenobite

Vigilance
Other creatures you control get +2/+2.
Creatures your opponents control get -2/-2.

Hushbringer

Flying, lifelink
Creatures entering or dying don't cause abilities to trigger.

Drana and Linvala

Flying, vigilance
Activated abilities of creatures your opponents control can't be activated.
Drana and Linvala has all activated abilities of all creatures your opponents control. You may spend mana as though it were mana of any color to activate those abilities.

Mishra's Groundbreaker

{T}, Sacrifice this artifact: Target land becomes a 3/3 artifact creature that's still a land. (This effect lasts indefinitely.)

Corrupted Zendikon

Enchant land
Enchanted land is a 3/3 black Ooze creature. It's still a land.
When enchanted land dies, return that card to its owner's hand.