Unnatural Selection
1U
Enchantment           
{1}: Choose a creature type other than Wall.  Target creature's type becomes 
that type until end of turn.


There are also many other uses for Unnatural Selection than just changing 
creatures into Legends so they die off. For example, it can combine nicely 
with Coat of Arms to give different creatures a common type. If you have 
three different creatures on the table, you can pay 2 mana to match two types 
up to the third, and give all three of them +2/+2.


Although you can't make creatures into walls, you can make walls into 
creatures so they can attack. Even though most walls aren't very good 
attackers, a few are. Cinder Wall is 3/3 for one mana (and it only dies if it 
blocks, not attacks), Wall of Razors is 4/1 First Strike for 2 mana, and 
Sunweb is a Mahamoti Djinn for 4. Not bad for one extra mana per turn...


Have you noticed that "King" cards like Eladamri or Lord of Atlantis give 
nice abilities to all creatures of one type, but usually aren't the type 
themselves? Change that Unnaturally! And this may be a pretty stupid use, but 
Unnatural Selection can use any spare mana you have lying around that might 
cause Mana Burn. Cards like Dark Ritual, Black Market, or Quirion Sentinel 
may produce too much mana. Or if you're just trying to get all your lands 
tapped to avoid Citadel of Pain damage or pump your Scoria Cat (or any of the 
other Prophecy cards), dump it all into Unnatural Selection. 


You can also have lots of fun with the new Flagbearer type. If your opponent 
tries to fry one of your creatures with a Shock, you can make one of his 
creatures a Flagbearer and they are then forced to hit one of their own guys. 
On the other hand, if they try to Giant Growth a creature, you can force them 
to cast it on yours. It works with almost any targeted ability! And if it 
keeps your opponent scared enough not to cast those spells, it might be a 
game-winning card!