Breeding Pond

({t}: Add {g} or {u}.)
As Breeding Pond enters the battlefield, you may
pay 4 life. If you don't, it enters the battlefield
tapped.
10 XP: {7}{g/u}{g/u}, {t}, Sacrifice Breeding Pond:
Choose two creatures you control. Create a copy
token of the combination of both creatures. (You choose which creature gives the power, which one gives
the toughness, mana value, name, and so on. Choose
one line of text on both creatures to put on the copy.)