Jolrael, Voice of Zhalfir

At the beginning of combat on your turn, up to one target land you control becomes an X/X green and blue Bird creature with flying and haste until end of turn, where X is the number of cards in your hand. It's still a land.
Whenever a land creature you control deals combat damage to a player, draw a card.

Zendikar's Roil

Landfall — Whenever a land you control enters, create a 2/2 green Elemental creature token.

Llanowar Loamspeaker

{T}: Add one mana of any color.
{T}: Target land you control becomes a 3/3 Elemental creature with haste until end of turn. It's still a land. Activate only as a sorcery.

Tatyova, Steward of Tides

Land creatures you control have flying.
Whenever a land you control enters, if you control seven or more lands, up to one target land you control becomes a 3/3 Elemental creature with haste. It's still a land.

Nissa's Zendikon

Enchant land
Enchanted land is a 4/4 Elemental creature with reach and haste. It's still a land.
When enchanted land dies, return that card to its owner's hand.

Embodiment of Spring

{1}{G}, {T}, Sacrifice Embodiment of Spring: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Wakeroot Elemental

{G}{G}{G}{G}{G}: Untap target land you control. It becomes a 5/5 Elemental creature with haste. It's still a land. (This effect lasts as long as that land remains on the battlefield.)

Risen Reef

Whenever Risen Reef or another Elemental you control enters, look at the top card of your library. If it's a land card, you may put it onto the battlefield tapped. If you don't put the card onto the battlefield, put it into your hand.

Tatyova, Benthic Druid

Landfall — Whenever a land you control enters, you gain 1 life and draw a card.