Elodin, Master Namer

As Elodin enters the battlefield, choose a colour.
Creatures you control of the chosen colour get
+1/+1.
Whenever you tap a land for mana of the chosen colour, add an additional mana of that colour.
At the beginning of combat each turn, creatures
you control gain your choice of flying, lifelink,
trample or haste.
At the beginning of each upkeep, sacrifice
Elodin, master namer unless you sacrifice another
creature.