When Merrow Harbinger comes into play, you may search your library for a Merfolk card, reveal it, then shuffle your library and put that card on top of it.
NM-Mint - $2.30
Lightly Played - $2.20
Moderately Played - $2.10
Heavily Played - $1.90
Damaged - $1.50
NM-Mint Non English - $2.30
Lightly Played Non English - $2.20
Moderately Played Non English - $2.10
Heavily Played Non English - $1.90
Damaged Non English - $1.50