Merora, Shaper of Seas

Merora, Shaper of Seas enters the battlefield
with a +1/+1 counter in it for each merfolk
you control.
Whenever a merfolk enters the battlefield, put a
+1/+1 counter on target creature you control.
When Merora, Shaper of Seas becomes blocked,
target creature you control gets +1/+1 for each
+1/+1 counter on the battlefield.