Plumed Merfolk

When Plumed Merfolk enters the battlefield, put
a +1/+1 counter on target creature you control.
If Plumed Merfolk's stalk cost was paid, instead distribute three +1/+1 counters among creatures
you control.
Stalk {3}{g}{g} (At the end of each block step, if there
is an unblocked creature attacking you, you may cast
this card for its stalk cost. If you do, choose an
unblocked creature attacking you. This creature blocks
that creature.)