Thalassic Harbinger

Thalassic Harbinger has hexproof as long as it's
not attacking.
Whenever you attack, choose up to two target
attacking creatures. For each of those creature,
create a Forerunner Role token attached to it.
(Enchanted creature gets +1/+1 and has "At the
beginning of your upkeep, sacrifice a Role attached to
this creature and draw a card.")