Wyvern Shore

Wyvern Shore enters the battlefield tapped.
At the beginning of your end step, if you
control four or more Islands and Wyvern
Shore isn't a creature, you may put three
+1/+1 counters on it. If you do it becomes
a 0/0 blue Dragon creature with defender
and flying. It's still a land.
Puddles, reasonably safe. Ponds, probably fine. Lakes, begin to worry me. Don't go near an ocean!