u got the spell gift in KB:TL which lets u use another skill from a unit again
plants are one of the easiest archer to kill in KB:TL (fireball/fire arrow)
the burning effectwill kill alot since they have low HP
and u can always use a ghost stack*(they regenreate hp by attacking and even growing in size)
but beware when they get too much leadership they will go red and attack everything
horseman/evil beholder/inqi's/royal snakes/priest
is a nice combo for the first island